Biggest Upsets in UFC History: Shocking Defeats and Unlikely Victories

It is highly possible to say that the UFC, being an organization with a penchant more than any other for producing some of the most high-octane entertainment and shocking moments in all of sports history, period-wise, scripted or unscripted, has seen quite many upsets on its tables, leaving people across all latitudes shattered. These are dramatic swings, the kind that shift not just fighters’s fortunes but also highlight the chaotic landscape in mixed martial arts. In revisiting some of the biggest upsets and most improbable wins, spanning over 25 years worth of events since its inception in 1993, we bring a unique light to the spirit competition that inspires us all through fighting as well as showcase an underdog quality that inspired fighters who came out on top where no one expected them to, changing not just history but our perspective. The biggest upsets in UFC history:

1. Matt Serra vs. Georges St-Pierre (UFC 69)

The year 2007 will forever be remembered as the one in which the UFC created what remains the biggest upset in MMA history. The champion, Georges St-Pierre (GSP), who was one of the all-time greats and arguably the most dominant fighter in his prime, took on Matt Serra, who opened as an enormous +850 underdog. GSP had the title, and for all intents and purposes, it seemed like no one would take that from him.

Result: Defying all expectations, Serra delivered a stunning first-round TKO to capture the welterweight title. This victory was a testament to Serra’s striking power and resilience, and it remains a landmark moment in UFC history.

2. Ronda Rousey vs. Holly Holm (UFC 193)

When she met Holly Holm in 2015, Ronda Rousey was the UFC women’s bantamweight champion—unbeaten and untouchable. Rousey, who was best known for her relatively short fights and armbar submissions, entered the Holm fight as a huge favorite against the then-ex-boxing champion, making it big in MMA.

Results: Holm executed the perfect game plan as she outclassed Rousey on the feet with her striking and footwork. Holm landed a head kick in the second round that knocked Rousey out, destroying her title hopes and surprising the UFC community. That one, which changed the course of women’s` MMA and spoke volume for vitality, is a developed and rounded strategy in this sport.

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3. Chris Weidman vs. Anderson Silva (UFC 162)

Anderson Silva, widely regarded as one of the greatest fighters of all time, was on a 10-fight title defense streak when he faced Chris Weidman in 2013. Silva’s striking prowess and elusive style made him a heavy favorite against the relatively unheralded Weidman.

Result: In a stunning turn of events, Weidman capitalized on Silva’s showboating, landing a left hook that knocked Silva out in the second round. This victory ended Silva’s legendary reign and marked the beginning of Weidman’s championship career.

4. Julianna Peña vs. Amanda Nunes (UFC 269)

With a 12-fight winning streak and eight straight as the UFC bantamweight champion, Amanda Nunes was widely regarded as not only the best female fighter in MMA history but also one of its all-time greats regardless of gender when she squared off against Julianna Peña back in November. A strong challenger, Peña was a heavy underdog.

Result: Peña was able to weather an early storm from Nunes on the feet and ultimately dominated, unloading a rear-naked choke in Round 2, capturing his first bantamweight title. Fans were thoroughly surprised by this upset, which showcased just how much of a warrior Peña is, making it to the list as one of the most surprising outcomes in recent UFC history.

5. T.J. Dillashaw vs. Renan Baro (UFC 173)

Considered one of the top pound-for-pound fighters ever at that time with a 32-fight unbeaten streak, Renan Barão entered his bantamweight title defense against T.J. Dillashaw in 2014 on quite an impressive run. Dillashaw, a major underdog, was just expected to be another name on Baro’s hit list.

Result: Dillashaw, fighting brilliantly and moving better and crisper with his striking as well. It took a while, but he finally secured the victory when he finished Barao in Round 5 via head kicks and punches. Aside from putting an end to Barão´s otherwise tediously dominant reign as champion, this win gave Dillashaw his first real taste of what it meant to be a top contender in the bantamweight division.

6. Michael Bisping vs. Luke Rockhold (UFC 199)

Michael Bisping stepped in on short notice to face middleweight champion Luke Rockhold in 2016. Rockhold had previously defeated Bisping and was heavily favored to retain his title.

Result: Bisping shocked the world by finishing Rockhold with punches in Round 1 to win gold at middleweight. Bisping was a long-time underdog but reached the pinnacle of his sport against Rockhold, who, in comparison, entered as an overwhelming favorite due to his skillset.

7. Nate Diaz vs. Conor McGregor (UFC 196)

Back in early 2016, Conor McGregor was undefeated as the UFC featherweight champion and on his way to a shot at lightweight gold when he fought Nate Diaz at welterweight on short notice. Heavy favorite McGregor had a reputation built on knockout power and precision.

Result: Diaz, on short notice, overcomes an early barrage from McGregor, then taps him out with a rear-naked choke in the second round. This loss set back the momentum of McGregor as well as put Diaz on the map regarding some incredible toughness and skill in what would become another classic UFC moment.

8. Forrest Griffin vs. Mauricio “Shogun” Rua (UFC 76)

Rewind to 2007, when former PRIDE champion Mauricio “Shogun” Rua was expected to dominate Griffin. He made his UFC debut against Ultimate Fighter winner Forrest Griffin as one of the UFC’s top light heavyweights at the time. Shogun was such a huge heavy favorite going into his fight with Griffin; it wasn’t supposed to be anywhere near close.

Result: With a gritty and relentless performance, Griffin pulled off possibly his most impressive victory in taking young Shogun with timely strikes and clinch work before sinking a rear-naked choke for her submission in round 3. It helped launch his career and his eventual title win.

9. Rose Namajunas vs. Joanna Jędrzejczyk (UFC 217)

Back in 2017, Joanna Jędrzejczyk was the UFC women’s strawweight champion and undefeated to boot. She looked all but invincible and was known for both her striking skills as well as her dominant performances. Jędrzejczyk entered the fight as a heavy favorite to defend her title.

Result: Namajunas knocked out Jędrzejczyk in the first round to become Strawweight Champion Shock of the Year. This was a shocker, and not just for the result but also for how easily Namajunas kept her cool and displayed her skills in some tight spots—it represented a change of their strawweight guard.

10. B.J. Penn vs. Frankie Edgar (UFC 112)

In 2010, B.J. Penn was the UFC’s lightweight champion and still considered one of the top fighters in mixed martial arts when he faced Frankie Edgar. Penn is a massive favorite with elite grappling and striking skills.

Result: The ever-energetic and wrestling-friendly Frankie Edgar used an intelligent game plan to out-strike Penn over five rounds, coming away with a unanimous decision victory. The win earned him the lightweight title and was one of the sweetest upsets in UFC history, launching Edgar’s championship reign.

These memorable upsets have etched a place in UFC history to secure the fact that no fight is ever preordained. Whether by spectacular knockouts or upsets from major game plans, this underdog wins not just fights but dignity in the octagon. As the UFC grows, fans can certainly anticipate many more upsets like the ones mentioned above that guarantee to keep things interesting in an ever-changing sport.