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Matt Serra walked into UFC 69 in April 2007 as roughly an +800 underdog. He was a former reality-show winner with a decent but unremarkable record, stepping in against Georges St-Pierre, a champion most people considered the future of the welterweight division. The fight lasted 3:25. Serra dropped St-Pierre with a right hand, followed him to the mat, and referee John McCarthy pulled him off a bloodied champion. It remains one of the biggest UFC upsets ever, and it still sets the bar for what a truly shocking night in the octagon looks like.
Upsets are the reason people keep buying pay-per-views. A dominant champion is boring until someone makes them look ordinary. Here are the nights that changed how fans, coaches and oddsmakers think about the sport.
Matt Serra vs. Georges St-Pierre (UFC 69, 2007)
The odds weren’t the only thing working against Serra. St-Pierre had just taken the title from Matt Hughes, and Serra had earned his shot through a season of The Ultimate Fighter rather than a long win streak. Most analysts framed the fight as a tune-up defence before GSP moved on to bigger names.
What Serra had was a heavy right hand and absolutely nothing to lose. He landed early, St-Pierre’s chin wobbled, and the fight was over before the broadcast team had finished explaining why the challenger had no path to victory. It’s still the benchmark for a betting longshot cashing in a title fight — and a reminder that a fighter with one elite weapon and zero pressure can be genuinely dangerous.
Holly Holm vs. Ronda Rousey (UFC 193, 2015)
Rousey had finished eleven of her twelve wins, most of them inside a minute. Holm came in as a boxing champion with limited MMA mileage and opened around +700 with several sportsbooks. The narrative was that she’d been given a payday, not a real chance.
Holm spent the first round circling, keeping distance and landing straight left hands. In the second she threw a head kick that caught Rousey flush on the jaw, then followed with ground strikes until the fight was stopped at 59 seconds. Ronda’s aura never really recovered. The result also shifted the entire conversation around women’s MMA — the division suddenly looked deeper and far less predictable than it had twelve months earlier, a change worth tracing through the careers of the fighters in any serious list of the best female MMA fighters.
Julianna Peña vs. Amanda Nunes (UFC 269, 2021)
Nunes was considered untouchable. Two belts, a long win streak, and wins over Rousey, Holm and Cris Cyborg. Peña was a former TUF winner who had been out of action for over a year and was priced anywhere between +550 and +700 depending on the book.
Peña didn’t fight carefully. She pushed forward, got taken down, scrambled up, and kept forcing Nunes into exchanges she didn’t want. Early in the second round she caught the champion standing, dragged her down and locked in a rear-naked choke. Nunes tapped. The upset mattered beyond the belt: the fighter widely regarded as the sport’s greatest woman had just been submitted by someone nobody had ranked in the top five of the division’s all-time conversation, which says plenty about how tough that conversation really is.
Leon Edwards vs. Kamaru Usman (UFC 278, 2022)
Edwards was losing clearly. Usman was ahead on the scorecards going into the final round of their rematch, controlling the pace and leaning on the challenger against the cage. The bout was being discussed as a comfortable, if dull, title defence.
With under a minute left, Edwards’ coach Dave Lovell told him to stop feeling sorry for himself and go win the fight. Edwards threw a head kick that landed on Usman’s temple and knocked him unconscious at 4:04 of round five. It’s the latest knockout in a title fight in UFC history, and arguably the sharpest single moment in a division’s modern era. Edwards had spent most of the fight losing by small margins; one technique with 56 seconds left erased all of it.
T.J. Dillashaw vs. Renan Barao (UFC 173, 2014)
Barao hadn’t lost in 34 fights. Dillashaw was a quiet, rangy bantamweight stepping in as an injury replacement, priced around +700. The expectation was a showcase defence for a champion building a case as the top pound-for-pound fighter in the sport.
What happened was a masterclass. Dillashaw’s footwork and constant angle changes confused Barao from the opening minute, and he landed a right hand that dropped the champion in the first round. He finished it in the fifth with a head kick and follow-up punches. Barao’s career never found the same gear afterward, and Dillashaw became a two-time champion. Few fights have done more damage to a reputation on both sides in one night.
The other nights worth remembering
- Michael Bisping vs. Luke Rockhold (UFC 199, 2016): Bisping took the fight on 17 days’ notice and knocked the champion out in the first round. He was around a +400 underdog.
- Gabriel Gonzaga vs. Mirko Cro Cop (UFC 70, 2007): Gonzaga ended Cro Cop’s UFC run with a head kick that’s still shown in highlight reels twenty years later.
- Nate Diaz vs. Conor McGregor (UFC 196, 2016): Diaz stepped in on 11 days’ notice, weathered early pressure, and submitted McGregor in the second round.
- Chris Weidman vs. Anderson Silva (UFC 162, 2013): Weidman was a +200ish underdog against the longest-reigning champion in UFC history and finished him in the second round.
What the great upsets have in common
Look closely at that list and the pattern isn’t luck. Three things tend to show up.
Style mismatches the market ignores
Holm’s footwork and straight punching solved a grappler who had never fought a disciplined boxer. Dillashaw’s movement broke a fighter who had only ever seen pressure. Bettors price wins and losses; they’re much worse at pricing how two specific skill sets interact.
Champions with long streaks and soft schedules
Dominant favourites get priced for who they’ve beaten, not how long it’s been since anyone made them uncomfortable. When a promoter has spent years protecting a champion’s aura, the market tends to keep believing in it a fight or two too long.
Underdogs with nothing to protect
Serra swung from the first exchange. Peña pushed forward without guarding her own back. Edwards kept throwing despite four rounds of evidence that it wasn’t working. The fighters who pull off the biggest upsets usually fight like the loss column can’t hurt them — because it can’t.
How to read a live underdog before the fight
Most upsets look obvious only in hindsight, but there are practical checks worth running on any underdog priced at +400 or higher. Start with age and mileage on the favourite: a 35-year-old champion with five title-fight camps in three years is a very different risk profile to a 29-year-old. Then check whether the challenger has a single fight-ending skill the favourite has genuinely struggled with before, even in victories. A kickboxer facing a wrestler with a suspect chin is a live dog regardless of the odds.
Schedule context matters too. Short-notice replacements cut both ways: fighters stepping in on two weeks are often in worse shape, but they’re also gameplanning freely, with no camp-long pressure to fight a particular way. Bisping proved that against Rockhold.
Finally, watch weigh-in and camp footage for signs of strain. A drained champion is the single most reliable predictor of an upset in this sport, and it’s usually visible before the cage door closes. The odds only tell you what the market believes. They don’t tell you what the fighters are actually bringing into the octagon.
