The Octagon is often referred to as the proving ground, a place where numbers, betting odds, and reputations are stripped away. While favorites usually prevail, the UFC has a storied history of nights where the impossible became reality. Following the seismic events of UFC 328, where Sean Strickland ended the 15-0 run of Khamzat Chimaev, the history books have officially been rewritten. Here are the five biggest UFC title fight upsets of all time, updated with the latest statistical data and betting history.
5. Sean Strickland vs. Israel Adesanya (UFC 293)
Before the Chimaev shocker, Strickland pulled off a nearly identical heist at UFC 293. Israel Adesanya was a -600 favorite, a reigning champion who had just reclaimed his belt with a definitive knockout of Alex Pereira at UFC 287. Moreover, Strickland had been knocked out previously by the Brazilian and was a late replacement for Dricus Du Plessis, a +450 underdog that few gave a chance.
The upset wasn’t just a win but a statistical anomaly. Strickland knocked Adesanya down in the first round, a rare feat against ‘The Last Stylebender’. Over five rounds, Strickland’s defensive shell allowed him to absorb only 42 significant strikes while landing 137 of his own. Adesanya, typically a volume specialist, was held to a dismal 34% striking accuracy. Strickland walked away with a dominant 49-46 unanimous decision and the 185lbs gold, silencing a stadium of 18,000 in Sydney.
4. Sean Strickland vs. Khamzat Chimaev (UFC 328)
For years, Khamzat Chimaev carried the aura of an MMA boogeyman, regardless of whether he competed at welterweight or middleweight. Heading into UFC 328, the Chechen star boasted a perfect 15-0 record and entered the bout as a heavy favorite to run through the division once again. That aura only grew stronger after his commanding performance against Dricus Du Plessis at UFC 319, where he racked up more than 21 minutes of control time and landed 529 significant strikes. With those numbers fresh in fans’ minds, many expected Sean Strickland to suffer a similar fate.
The narrative seemed even more convincing given that ‘Tarzan’ had already lost twice to Du Plessis at UFC 297 and UFC 312. So when Chimaev went on to dominate the South African, many fans struggled to see how Strickland could possibly flip the script at UFC 328. However, Strickland defied the oddsmakers in a gritty five-round war.
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Chimaev secured 9 takedowns on 13 attempts, controlling much of the first round. But as the fight progressed, Strickland’s legendary cardio took over. Strickland outlanded Chimaev on the feet, utilizing his relentless lead jab that resulted in a 48-47, 47-48, 48-47 split decision victory. By the fifth round, Strickland’s volume, landing 133 total strikes to Chimaev’s 98, cemented his status as a two-time champion and handed Chimaev his first professional loss.
3. Holly Holm vs. Ronda Rousey (UFC 193)
In 2015, Ronda Rousey was the most dominant force in sports. She was a -1250 favorite, having finished her previous three title defenses in a combined 64 seconds. Holly Holm, a world champion boxer but an MMA underdog at +800, was seen as another lamb to the slaughter.
The statistics told a story of tactical perfection. In just under six minutes of cage time, Holm outlanded Rousey 38 to 17 in significant strikes. Holm successfully defended all of Rousey’s signature clinch attempts, neutralizing the Judo Olympian before landing a flush left high kick at 0:59 of Round 2 in front of over 56000 fans. It was the first time Rousey had ever been taken past the first round in a victory or loss, ending a bantamweight title reign that many thought would never fall.
2. Julianna Peña vs. Amanda Nunes (UFC 269)
Amanda Nunes entered UFC 269 on a 12-fight win streak spanning seven years. She was the WMMA GOAT, and a gargantuan -1100 favorite. Julianna Peña, coming off a long layoff and inconsistent performances, was a massive +700 underdog. The upset was born in a chaotic second round.
After being dominated in the first, Peña decided to trade. She landed 79 significant strikes to Nunes’ 46, effectively breaking the champion’s spirit. Nunes, who had never shown signs of fatigue in the past, became gassed under Peña’s pressure. At 3:26 of the second round, Peña secured a rear-naked choke without even having her hooks in, forcing a tap and ending one of the most storied title reigns in MMA history.
1. Matt Serra vs. Georges St-Pierre (UFC 69)
The gold standard for UFC upsets remains Matt Serra’s 2007 welterweight title victory over Georges St-Pierre. Serra had earned his shot via The Ultimate Fighter 4, while GSP was the -1300 favorite and the blueprint for the modern MMA athlete.
Statistically, Serra had no business winning. He was significantly shorter, had a reach disadvantage, and was known primarily as a grappler. However, at 3:25 of the first round, Serra landed a looping right hand behind the ear that scrambled GSP’s equilibrium. Serra followed up with a flurry of unanswered strikes on the ground to secure the TKO. Even today, with betting odds often reaching extreme heights, the +1300 underdog Serra remains the ultimate proof that in a fight with four-ounce gloves, everyone is vulnerable.
Kshitiz Kumar Singh is a UFC Writer at NY Fights with over three years of experience in sports journalism and content creation. Known for his sharp storytelling and passion for combat sports, he has written in-depth features on stars like Brock Lesnar, Randy Couture, and Ilia Topuria. Before joining NY Fights, Kshitiz worked as a UFC Editor at EssentiallySports while currently serving as a WWE Editor at FirstSportz. His admiration for legends like Georges St-Pierre continues to inspire his detailed and engaging MMA coverage. Whether he’s covering the Octagon or the squared circle, Kshitiz is committed to delivering accurate, high-quality content. Outside the world of sports, he’s a dedicated cinephile, often found practicing monologues from his favorite Al Pacino films, combining his love for cinema with storytelling.