Biggest UFC Upsets by Odds: When Underdogs Cashed In
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Underdogs win in the UFC more often than most fans think.
Favorites win roughly 60 to 65 percent of fights, according to a Fightful analysis of historical lines. That leaves underdogs cashing in more than a third of the time. MyMMANews' data lands close: underdogs beat favorites about 32 percent of the time.
The odds below are reported lines from the cited sources — not OctagonStats' own numbers. Lines move, so figures vary by book and by when they were captured. This is a look at history, not betting advice.
Matt Serra vs. Georges St-Pierre — +700 to +850
The line: Serra +700 at close, +850 at peak. St-Pierre -1000 to -1300.
The event: UFC 69, April 7, 2007, Houston.
The result: Serra won by first-round TKO.
Matt Serra earned his title shot by winning The Ultimate Fighter: The Comeback. Few gave him any chance against Georges St-Pierre, the reigning welterweight champion.
Serra clipped St-Pierre with an overhand right early and never let up. The stoppage came 3:25 into round one. Sherdog's Prime Picks notes that only four -1000 favorites have ever lost in the UFC — and St-Pierre was the first.
Some books listed Serra as an 11-to-1 underdog at peak. By closing line, +700 remains one of the longest prices ever cashed in a UFC title fight.
Holly Holm vs. Ronda Rousey — +830
The line: Holm +830, Rousey -1400. Peak lines reached +1250.
The event: UFC 193, November 14, 2015, Melbourne.
The result: Holm won by second-round knockout.
Rousey was the biggest star in MMA. Holly Holm was a former boxing champion with just two UFC wins to her name.
Holm dominated round one, then landed a head-kick knockout 55 seconds into round two. Las Vegas books got crushed — underdog wagers on Holm outnumbered Rousey bets five to one, according to SBC News. Dana White called it "without doubt the biggest upset in the sport's history."
By most widely cited closing lines, this is the biggest underdog win in UFC history.
T.J. Dillashaw vs. Renan Barão — +765
The line: Dillashaw +765 at peak (Barão -1250). The closing line sat near +710.
The event: UFC 173, 2014.
The result: Dillashaw won by fifth-round TKO.
Renan Barão had not lost in nearly nine years — a 32-win run spanning the WEC and UFC. T.J. Dillashaw was a former Team Alpha Male prospect stepping in as a big underdog.
Dillashaw cracked Barão early and beat him for nearly five full rounds. A head kick and follow-up punches midway through the fifth ended it. Sherdog called it the latest finish in UFC bantamweight history at the time.
The rematch told the story of how far the odds swung: Dillashaw went from a +710 underdog to a -200 favorite.
Julianna Peña vs. Amanda Nunes — +650
The line: Peña +650 (DraftKings), Nunes -1000.
The event: UFC 269, December 11, 2021, Las Vegas.
The result: Peña won by second-round submission (rear-naked choke).
Amanda Nunes was on a 12-fight win streak and widely regarded as the greatest women's fighter of all time. Julianna Peña entered as a 6½-to-1 underdog, per ESPN.
Round one looked like a mismatch. Round two did not. Peña came out jabbing, backed the champion up, took her down, and locked in a rear-naked choke.
ESPN Stats & Info ranked it the second-largest underdog to win a women's title fight in UFC history — behind only Holm vs. Rousey.
Why Title Fights Produce the Biggest Shocks
Three of the four upsets above came in title fights. That is not a coincidence.
Champions attract lopsided betting on name recognition. Books price them long. When a favorite sits at -1000, the line implies a win probability above 90 percent. MMA is a sport where one punch or one choke can erase that math in a single exchange.
The pattern cuts both ways. Favorites win most fights. But over a long run, underdogs at long odds do not need to win often to matter — and in the UFC, they win roughly one in three.
One more note on the numbers: past upsets do not predict future fights. This article is a record of what happened, not advice on what to bet.
Common Questions
### What is the biggest UFC upset by betting odds?
Holly Holm at +830 over Ronda Rousey is the most widely cited closing-line upset. Matt Serra peaked at +850 against Georges St-Pierre. Which ranks first depends on whether you use closing or peak lines.
### How often do UFC underdogs win?
About a third of the time — roughly 32 to 38 percent of fights, depending on the dataset and time frame.
### What is the biggest title-fight upset in UFC history?
By the odds, Serra vs. St-Pierre for the men and Holm vs. Rousey for the women. ESPN Stats & Info ranked Peña vs. Nunes second among women's title fights.
Sources
- Sherdog — Prime Picks: Biggest Betting Upsets in UFC History (sherdog.com)
- BookMaker.eu — The biggest upsets in UFC history and how much you could've won on Holly Holm (bookmaker.eu)
- SportsBoom — The Biggest Upsets in UFC History (sportsboom.com)
- LowKick MMA — Biggest Underdog Upsets In UFC History (lowkickmma.com)
- Bleacher Report — Julianna Pena Beats Amanda Nunes via Submission to Win Title in UFC 269 Upset (bleacherreport.com)
- Action Network — Updated UFC 269 Odds: Betting Lines for Oliveira vs. Poirier, Nunes vs. Pena, More (actionnetwork.com)
- ESPN — The world doubted Julianna Peña could beat Amanda Nunes at UFC 269, but Peña believed (espn.ph)
- SBC News — Ultimate Underdog! Holly Holm's shock UFC 193 victory KOs Vegas bookmakers (sbcnews.co.uk)
- Fightful — How Accurate Are UFC Betting Odds At Predicting Finishes And Upsets (fightful.com)
- MyMMANews — What Percentage of Underdogs Win UFC Fights? (mymmanews.com)
Fight data compiled from public statistical sources (ufcstats.com) and Wikipedia (CC BY-SA). OctagonStats is an independent database, not affiliated with UFC / TKO Group.