Now that horse racing is well into its second decade of the 21st century, we’ve had the chance to witness a large crop of horses come in and leave lasting marks on the sport. The benchmark for all-time great comparison always ends up being Secretariat, and on some level, there really isn’t a horse that comes close to Big Red’s legacy. But it’s always tantalizing to consider who could match up and how they’d do.

The end of this year’s racing season culminated with the Breeders’ Cup Classic, as always. This time around, a galvanizing colt emerged in Flightline (trained by John Sadler). After his glorious triumphs at Keeneland and Del Mar before that, many experts and fans were quick to dub him one of the greatest horses of all time. The Secretariat comparisons were rampant. Has he rightfully earned that comparison? We’ll dive a bit into that later.

We previously published this piece a couple of years ago, and since then, a lot of excellent new horses have emerged. We also left off quite a few fan favorites, so it’s only fair that we update the list and expand it to 15 (yes, we previously omitted Curlin, and we are very sorry about that!).

A lot has changed in the horse racing world since 2000. Breeding has become the main stream of revenue for top racehorses, and protecting that asset has become crucial. Thus, horses typically don’t race as often or as long as they used to. It becomes tough to really measure the true merits of a potential all-time great, especially when you compare them not just to Secretariat, but other legends of the past like Seattle Slew, Ruffian, Spectacular Bid, Affirmed, Alysheba, A.P. Indy, Cigar, and the list goes on and on.

But then again, finishing times and Beyer speed numbers are objective truths in the sport, and many of the horses on this list do stack up. With that in mind, enjoy our updated – now 15 – greatest racehorses of the 21st century!

15. Wise Dan

To this day, Wise Dan is the only horse to ever win the same three Eclipse Awards in consecutive years: Champion Older Male, Champion Male Turf Horse, and American Horse of the Year. Of the horses on this list, Dan is the only one to primary compete on turf, and sometimes as a sprinter. Nonetheless, in those divisions, the gelding was nearly unstoppable, winning almost every Grade I race in back-to-back years, including the Woodbine Mile and the Breeders Cup Mile.

As a gelding, the owners of Dan had a greater incentive to race him more often, and he continued competing well into his seventh year. However, frequent injuries prevented Dan from capturing the same glory as his earlier years. Nonetheless, Wise Dan raced a whopping 31 times, capturing 23 wins, both tops of any other racehorse on this list. Shades of John Henry. He was inducted into the Hall of Fame in 2020.

“He’s living with his brother Successful Dan, here at our farm. He’s happy as can be. He gets a lot of visitors to see him,” his trainer Charles LoPresti remarked upon Dan’s retirement. “He has a different personality than most horses.”

Best Race: The 2013 Breeders Mile, the second of his back-to-back triumphs. After stumbling early out of the gate and seemingly out of the race, Dan weathered suicidal early fractions to close at an incredible pace and steal the race from Za Approval. They really don’t make horses like Wise Dan anymore.

14. Accelerate

Accelerate, whose bloodline includes legends such as Danzig and Raise a Native, was a bit of a late bloomer, having not raced at all until his 3-year-old season. Even then he was slow to develop, but once he got going, he racked up an impressive string of results. That culminated in one of the best 5-year-old seasons for a stallion, including triumphs in the Pacific Classic at Del Mar as well as the Breeders Cup Classic in 2018. His career also included a pair of big victories over Arrogate, who also ranks on this list. He’s also a rare stallion to race as many times as he did: 23 times overall, with 10 victories and over $6 million in career earnings.

“That was about as good as it gets,” Rosario said after Accelerate’s Classic win. “That horse is simply unbelievable. I’m so happy for the owners and John. It was a great performance. He has so much heart.”

Best Race: The 2018 Breeders Cup Classic of course. After starting at the outside gate and being forced four wide for most of the race, Accelerate closed the final stretch in stunning fashion to surge past Mendelsson and Dialed in and hold off a late challenge from Gunnavera to win by a length. He also broke trainer John Sadler’s long Breeders Cup losing streak.

13. Invasor

The Legend from Uruguay was nearly perfect in his career, winning 11 of 12 races. After capturing the Uruguayan Triple Crown, Invasor would conquer North America, winning the final nine races of his career, including racing’s two richest prizes: the Breeders’ Cup Classic and the Dubai World Cup – one of only five horses to do so. A deadly finisher, Invasor also had folk hero credentials, and was a national treasure in his native Uruguay.

Luis Costa Belata, a Uruguayan horse owner and racing legend, once stated, “Since Invasor has gone to the United States, every time he runs, all the simulcast halls are crowded with people who come to see him and bet on him. They shout and cheer for him as if Uruguay was playing in the finals of the World Cup. They treat the horse as if he were still their own. No one can imagine what it’s like. He’s become a national hero.”

Best Race: The 2006 Breeders’ Cup Classic, in which the colt outlasted a packed field and chased down the heavy favorite, Preakness winner Bernardini, on the final stretch. A close second is Invasor’s dominating victory at the Dubai World Cup that cemented his legend, and which was sadly the final race of his career before an injury forced him into early retirement.

12. Tiznow

The first great racehorse of the 21st century, Tiznow was notoriously picky, often bothered by conditions such as hard surfaces or rainy weather, as well as being resistant to jockey Chris McCarron’s whipping. “He’s a California horse all the way. I think in a way it shows how intelligent he is,” said an assistant at his home barn WinStar.

Nonetheless, Tiznow’s trainers and owners found ways to tactically harness the colt’s abilities, empowering him to a remarkable run of results that included back to back victories at the Breeders’ Cup Classic (he’s still the only horse in history to pull off that feat). Tiznow won 8 of 15 career races and captured 2000 Horse Of The Year honors, the first California-bred racehorse since Swaps to win the award.

Best Race: Tiznow lorded over a spectacular field at the 2000 Breeders’ Cup Classic that included Kentucky Derby winner Fusaichi Pegasus, Belmont winner Lemon Drop Kid and Irish champion Giant’s Causeway. But his victory the next year at the Breeders’ was even more impressive, considering he’s still the only horse in history to win the race back-to-back. Despite being reigning Horse Of The Year and the defending champion, Tiznow was only the fourth betting choice going into the race. He still overcame the heavy favorite Aptitude, winning the race by a nose over Sakhee, and cementing his legend status.

11. Gun Runner

The first half of Gun Runner’s career showed promise, but was relatively unremarkable. After winning a few early races, he ran a close third in the Kentucky Derby, followed by a slew of aggravating runner-up performances. But the Steve Asmussen-trained colt had a stunning late-career renaissance, winning seven of his final eight races (his only loss being to the indomitable Arrogate in Dubai), while posting eye-popping times in the process.

Chris Baker, C.O.O. of Three Chimneys (Gun Runner’s barn), best described Gun Runner’s attributes: “Pedigree. Conformation. Athleticism. Just the way he always carried himself – just very smart, intelligent, classy. Easy-moving horse, kind of scope-y and light, but in a good way – just an athlete.” 

Best Race: The 2017 Breeders’ Cup Classic, in which Gun Runner finally turned the tables on his arch nemesis Arrogate. The colt trounced the field en route to winning Horse Of The Year, but the win was even more impressive considering the fluke-like results earlier that day at Del Mar. Despite a perceived track bias where frontrunners on the rail were at a disadvantage, Gun Runner prevailed effortlessly over second-place Collected, while perennial thorn-in-the-side Arrogate was a non-factor from the start.

10. California Chrome

In many ways, California Chrome was the gift that kept on giving, as he raced until he was six years old, winning countless big races along the way. His three-year-old season was a dazzling one. Despite a lack of pedigree and a perceived bias against him from the rest of the racing community, Chrome was a tactical and physical beast, capturing six consecutive races including the Kentucky Derby and Preakness Stakes in emphatic fashion. A poor ride by Victor Espinoza in the Belmont saw Chrome fall just short of the Triple Crown, but he managed to garner Horse Of The Year honors with gusto.

After a mid-career lull (perhaps due to infighting amongst his owners), he had a spectacularly resurgent five-year-old campaign, winning 7 of his next 8 races including a sterling win in the Dubai World Cup. His only defeat came in an all-time classic duel against the titan Arrogate (more on that race later), but nonetheless, California Chrome managed to capture another Horse Of The Year gong while stamping his name into horse racing folklore as not just one of the best horses of this century, but one of the most popular. Savvy branding helped give Chrome his rockstar aura, with fans donning his colors and chanting his name wherever he raced.

Not only was he a great athlete, but he was a born performer and entertainer. “He’s a ham,” co-trainer Alan Sherman once said, referring to the colt’s vogue-ish, cornball personality. Chrome was even known to deliberately “pose” for cameras by gritting his teeth into a smile and perking his ears upon hearing them click. It’s no wonder he became such a crowd favorite.

Best Race: The 2014 Kentucky Derby, in which he made due on his mountain of hype and proved all the skeptics and nay-sayers wrong. Here, Chrome ran the perfect race, keeping pace with the leaders before taking command down the back stretch and comfortably pulling away around the turn. His Preakness win might have been more dominating, but the Derby win was the watershed moment of his career.

9. Knicks Go

Largely unheralded before he even debuted – mostly due to a perceived low pedigree (his sire is Paynter, whose most notable result was runner-up in the 2012 Belmont Stakes) – Knicks Go had just about the most up-and-down career of any horse on this list. He initially stunned the racing world as a 2-year-old with a longshot 70-1 win in the Breeders Futurity, followed by a 40-1 longshot runner-up finish in the Breeders Juvenile, but his 3-year-old season was an epic disappointment that saw him capture 0 wins in 8 starts.

But in his 4-year-old season, Knicks Go found incredible form under new trainer Brad Cox, romping to several wins including at Oakmont Park and a 1 1/16 mile track record-setting win at Keeneland. His 5-year-old season saw him become the best racehorse in the world, racking up wins at the Pegasus World Cup, the Whitney, and finally, the Breeders Cup Classic. This is a horse that constantly proved the doubters wrong.

Toward the end of his career, those who worked with Knicks Go would constantly remark about how consistently relentless he was. “He is one of the top handicap horses in the country now. He’s a top horse. This is what you get up for every day, seven days a week, long days for moments like this,” Cox said.

Best Race: Knicks Go’s tried-and-true strategy was to set the early pace and hold it the entire way. That typically worked at shorter distances, but there were always questions about his abilities at 1 1/4 miles. Those criticisms finally went out the window after his dynamic win in the 2021 Breeders Cup Classic over a sterling field that included Triple Crown stars Essential Quality, Medina Spirit and Hot Rod Charlie. Here, Knicks Go went immediately to the lead and never let up, finishing just off the Del Mar track record set by Candy Ride. “KNICKS GO’S A SUPERSTAR” yelled Larry Collmus, without question one of the most unlikely of the 21st century.

8. Curlin

For all the horses who didn’t make it onto our original list, we received by far the most backlash for our omission of Curlin. And you know what? We hear you! And after going back and reconsidering, we now see just how egregious that snub was. Sorry Curlin and Curlin fans!

One of the few horses to win back-to-back Horse of the Year honors (2007 and 2008), Curlin immediately established himself as a superstar early in his career with a victory in the Preakness over Derby winner Street Sense and a Belmont runner-up finish to surprise winner, the filly Rags to Riches. But after that, he kept the momentum going, emerging victorious in the Breeders Cup Classic in one of the wettest, sloppiest tracks the race had ever seen. His 4-year-old season notched big-money wins in the Dubai World Cup, the Stephen Foster Handicap and the Woodward Stakes. That winning streak saw him pass Cigar as the richest racehorse in history.

“What a horse,” jockey Robby Albarado said after winning the Breeders. “Curlin is like a limousine and I am just along for the ride.” His stud career has been just as prolific, with offspring including Grade I winners Keen Ice, Malathaat, Vino Rosso, Exaggerator and Nest.

Best Race: The 2007 Breeders Cup Classic, in which he overcame sloppy conditions at Monmouth Park as well as an iffy middle-of-the-pack start to eventually accelerate down the back stretch for a solid 4 1/2 length victory over Hard Spun and Street Sense.

7. Justify

Justify became just the second horse in 40 years (and Bob Baffert’s second) to capture the Triple Crown. To some extent, his triumph isn’t talked about enough since it so quickly followed American Pharoah’s. He also only raced 6 times in his entire career, otherwise he’d be much higher on this list. Nonetheless, he went completely undefeated and never looked so much as bothered by any horse he faced. He was a flippant runner, brushing his rivals aside while looking like he was barely breaking a sweat.

“You can walk up to him and he might give you three, four, five seconds, and then he’s done with you. He’ll try to bite your head off. It’s not in a mean way. He’s just a big, tough horse. He’ll run you out of the stall,” said Baffert. It’s no surprise then that Justify was such a merciless competitor. With just a single Grade I race under his belt (an easy 3-length victory at Santa Anita), he and jockey Mike Smith crashed the 2018 Triple Crown party as the intriguing wildcard choice, but they ultimately proved to be an unstoppable force (despite a nervy win on a sloppy track at the Preakness). Frustratingly, Justify’s owners WinStar opted to retire him to stud early, knowing full well how much money was on the line. In that sense, Justify is a rare case; both a bona fide legend and a case of “what could’ve been?” Revelations of possible doping violations have also slightly affected his and trainer Bob Baffert’s legacy.

Best Race: His breezy Belmont Stakes win was the cherry on top of what wound up being the end of his career. Perhaps a tad less thrilling than American Pharaoh’s run, Justify’s win never really looked in doubt, and he put the hammer down in a classically emphatic performance. It also solidified Baffert’s status as racing’s all-time greatest trainer.

6. Rachel Alexandra

One of the best fillies since Ruffian, Rachel Alexandra was the first racehorse of the new millennium to achieve true rockstar status. Versatile and domineering, she was excellent at breaking out of the gate and holding onto leads, a true accomplishment considering the stacked competition she regularly faced (although sadly, we never got to see her and Zenyatta face off).

In addition to becoming the first filly to win the Preakness in 85 years, Rachel Alexandra won 13 of 19 races (including 9 in a row) under trainer Steve Asmussen and jockey Calvin Borel. Huge crowds flocked to see her in the summer of 2009, when she captured thrilling victories at Belmont Park, Monmouth and Saratoga. Her relaxed, calm and collected demeanor gave her a ruthless edge over her opponents and endeared her to fans.

“The first moment when I realized what it was like to be associated with Rachel Alexandra was when we walked over for the Preakness and left the barn,” Asmussen once said. “I’ve been associated with some great horses and champions, but I’ve never been associated with a horse who everyone was rooting for like they we were rooting for her. People you ran against were rooting for her. It was an amazing feeling.” Now long-retired, crowds still flock to visit her at her home in Lexington, KY.

Best Race: The 2009 Preakness Stakes, where she broke cleanly on the far outside and went wire-to-wire to hold off another classically late charge from Kentucky Derby winner Mine That Bird. The overwhelming favorite going into that race, her win proved her metal against a field of tough male horses who were all gunning for her from the start. Also, her dominating win in the muddy slop of the Haskell Invitational is a simply amazing performance.

5. Arrogate

The second Bob Baffert-trained horse to make this list, Arrogate’s unprecedented late 2016 and early 2017 campaigns are already the stuff of racing legend. In that short span of time, he won seven straight races (including four Grade I events), captured the Breeders’ Cup Classic and the Dubai World Cup, shattered several track records, and became the highest-earning racehorse in history – all while earning lavish Secretariat comparisons along the way.

But after returning from Dubai, Arrogate was sadly never the same. After losing three races in a row, he was swiftly retired to stud, thus putting a lid on any and all GOAT-status arguments. (His drop-off also coincided with archrival Gun Runner’s late-career second-act). Even sadder, Arrogate passed away at the age of 7 after suffering from a sudden neurological condition. When all is said and done though, the colt rightfully deserves to be considered one of the century’s very best.

“It takes a lot to make me cry, but I cried [Tuesday] morning when I heard the news,” Baffert said upon learning of Arrogate’s tragic death. “I’ve never had a horse that threw in four magical races in a row that were off the charts. He was just brilliant. I would’ve thrown Arrogate against [Secretariat]. I would never say that at the time – it’s sacrilegious – but believe me, he was that kind of horse.” RIP.

Best Race: There are SO many to choose from. On the one hand, the 2016 Breeders’ Cup Classic that saw him chase down California Chrome by a nose was one of the great final stretch duels of all time. But on the other, Arrogate’s greatest race has to be the Dubai World Cup the following year. After a disastrous start out of the gate, he’d go all the way from last to first, overcoming a 12-length deficit to blow past a crowded field that included rivals Mubtaahij and Gun Runner. A mind-boggling win, and the final one of his career.

4. American Pharoah

American Pharoah finally broke the curse and pulled off the greatest feat in thoroughbred racing by winning the Triple Crown in 2015, the first horse to do so since Affirmed in 1978. But beyond that incredibly special moment, Bob Baffert’s flagship colt gave us the sport’s most exciting six-month run of the 21st century.

Right from his earliest races, Pharoah looked like the real deal – a fully-fledged competitor with pedigree, athleticism, skill, and an ability to ruthlessly close out races. After winning his fourth race in a row at the Arkansas Derby, there was a cautious optimism that he had what it took to win the Triple Crown, a feeling that only multiplied after his assured Derby win. After then cruising to an eye-popping 9 1/2 length win at the Preakness, anticipation going into the Belmont had hit fever pitch. Never mind the many times we’d been let down in the past (Sunday Silence, Silver Charm, Real Quiet, Charismatic, War Emblem, Funny Cide, Smarty Jones, Big Brown, I’ll Have Another and California Chrome all came up short in my lifetime). This one felt different though. How gloriously we were rewarded.

“We felt we had brilliance in him,” said owner Ahmed Zayat. “His demeanor, his aura, his conformation, the way he moved. He just did everything right.” Following his Triple Crown victory, Pharoah continued his winning ways at the Haskell, but narrowly missed out at the Travers (known by many as the “Graveyard of Champions”). But he closed out his career in storybook fashion with a domineering, 6 1/2-length triumph at the Breeders’ Cup: “A HORSE OF A LIFETIME!” yelled announcer Larry Collmus at race’s end.

“American Pharoah loved human contact. He was a very sweet horse and is still very sweet. He loves people, will put his head in your lap. I’m probably closer to that horse because of his temperament,” Baffert said recently. “It has been a privilege to train this horse. This is the greatest horse I’ll ever see.”

Best Race: We all remember collectively screaming at our televisions, half in ecstasy and half in relief, when we saw that Frosted had run out of steam on the final stretch, clearing the way for jockey Victor Espinoza to guide Pharoah’s historic triumph at the Belmont. I’ve probably watched the clip of the race a hundred times and I still get goosebumps. Even from the TV, the atmosphere coursing through Belmont Park was like that of a Rolling Stones concert in their prime. Not only was it the best moment in recent racing history, but it’s one of the great sports moments of our time. But would he beat any of the horses listed above him? I’m so sure, to be honest!

3. Ghostzapper

“Few horses have devastated their opponents in so many ways, at so many distances, and in such fast times,” said horse racing journalist Steve Haskin of 2004 Horse Of The Year Ghostzapper. Over the course of his sterling career, the Bobby Frankel-trained colt proved to be one of the most versatile and consistently fast horses to ever race.

The large dark bay had a gigantic stride and devastating closing speeds, which allowed him to dominate at 7 Furlongs, a mile, 1 1/8 miles and 1 1/4 miles. Simply put, Ghostzapper was a machine through and through, earning comparisons to the likes of Cigar and Citation. He would win 9 of 11 races in his career (including his final 6), most by huge margins. He even won the Philip Iselin Handicap at Monmouth by a whopping 11 lengths, and somehow hit 128 on the Beyer Speed rating, the highest ever assigned since its inception (and highest since Secretariat). Thus, Ghostzapper might be the fastest pure runner on this list. An injury sadly cut his career short, which is the only reason he’s not higher. In that respect, Ghostzapper remains a slightly underrated figure in the sport. “I know you dream of winning the Kentucky Derby, but the best dream is to know you have the best horse,” said Frankel.

Best Race: The most impressive victory of Ghostzapper’s career probably came at the Breeders’ Cup Classic, in which he made good on his buzz with another dominating victory over a stacked field. In that one, he also managed to break the 1 1/4 mile Belmont track record! But the best race of his career was his epic photo-finish victory over Saint Liam in the Woodward Stakes earlier that year – one of the best duels in recent memory.

2. Zenyatta

The closest any American racehorse has come to running a perfect, undefeated career in at least 20 starts was Man O’ War all the way back in the 1920s. A small handful of others have come agonizingly close since, and Zenyatta was one of them. From 2007 to 2010, the massive bay filly won 19 consecutive races (breaking Cigar and Citation’s long-held record), most of them in jaw-dropping, dramatic fashion.

With Hall of Fame jockey Mike Smith aboard, Zenyatta became notorious for her blistering closing stretches. That meant she often gifted the front runners a huge lead before clawing her way back and narrowly overtaking them at the wire. Throughout that winning streak, Zenyatta developed a rabid following, with fans traveling across the country to watch her last several races. Sellouts and record TV ratings followed her wherever she went, and her style of racing had the tendency to whip crowds into a fanatical frenzy. A true rockstar for the sport with an utterly charming personality to boot. “She loves herself…she’s a total diva,” a member of her team once said. “You know a high-performance car when you hit a gear? That’s what it feels like. You can feel her hit a gear. When she hits one, you’re like, whoa,” said Mike Smith.

Of course I’d be remiss to mention the only blemish of her career – her last race in the Breeders’ Cup Classic of 2010 – in which she made her final charge just a hair too late, only barely losing to Blame by half a nose. A couple extra yards and she would’ve caught him, and her perfect career would’ve remained intact.

Best Race: “This is un-bee-lievable!” shouted announcer Trevor Denman at the conclusion of the 2009 Breeders’ Cup Classic, in which Zenyatta pulled off one of the most astonishing victories in racing history. A horrible start out the gate saw the filly fall behind in last place, forcing her to make up the largest deficit of her entire career. “If she wins this she’ll be a superhorse,” Denman said as she needled her way through the field, slowly picking up ground. Sometimes things seem impossible to the human eye; seeing Zenyatta come around the turn and blitz her way down the final stretch for an incredible finish win over Gio Ponti is truly a sight to behold. I mean seriously…HOW? “What a performance, one we will never forget,” said Denman. Indeed, a race for the ages.

1. Flightline

Flightline only raced a total of six times, but he ran possibly six of the greatest races that have ever been run. An early injury prevented him from competing in the 2021 Triple Crown races, throwing another wrench into the GOAT debate, but once he debuted, nobody else came close to touching him.

Simply put, there proved to be no strategy to beat Flightline. You can’t try to challenge him early by setting an early pace, or else you’re just gonna tire yourself out. You also can’t ease off the pace and hope to come from behind; he’ll just build an insurmountable lead and breeze to victory down the stretch. You were damned if you did, and damned if you didn’t, as demonstrated by Country Grammer in the Pacific Classic and Life Is Good in the Classic.

Flightline simply dominated every single time, winning by record-breaking margins. Overall, Flightline’s victories included: a 13 1/2 length win in the Maiden (Santa Anita), 12 3/4 length win in the Allowance (Del Mar), 11 1/2 length win in the Malibu Stakes (Santa Anita), 6 length win in the Metropolitan Handicap (Belmont Park), 19 1/2 length win (!!!!) in the Pacific Classic (Del Mar), and an 8 length win in the Breeders Cup Classic (Keeneland). He also recorded a 126 Beyer Speed at Del Mar, second only to Ghostzapper in the modern era. It’s a shame that he won’t race again, but in this day and age, it’s to be expected. Given these Secretariat-like results, even in just a small sample size, there is way too much money to be made in his stud career. Regardless, racing fans will never forget this epic run of success from the most ruthless horse I’ve seen in my lifetime.

“He never has hidden his talent. He has always shown great ability from day one. He is in great form and is an incredible athlete,” John Sadler said at the Breeders Cup Classic. “This is one of the great horses of all time – I think history will show that.”

Best Race: It’s a tie. Obviously, winning the Classic in the way that he did – with all the pressure and attention of the racing world and beyond on jockey Flavien Pratt – definitely qualifies. In that race, Life Is Good gave him his best challenge, dueling him until the final stretch. Even then it wasn’t enough, as Flightline pulled away to an 8-length win, punctuating his career. But take a look at his win in the Pacific Classic, in which he pulled away in jaw-dropping fashion to win by a whopping 19 1/2 lengths over Country Grammer. It’s the most impressive performance racing has seen since Secretariat’s Belmont moment. We didn’t get to see enough of Flightline, and it’s very possible we will never see another horse as great as him.

Honorable Mentions: Wise Dan, Beholder, Afleet Alex, Smarty Jones, Azeri, Black Caviar, Point Given, Saint Liam, Havre de Grace, Maximum Security, Candy Ride, Authentic, Street Sense, Medaglia d’Oro