MMA’s Biggest Upsets: When the Underdog Shocked the World

29 August 2025

Let’s be honest—MMA is unpredictable. One minute, a fighter is dominating the Octagon, and the next? Lights out. That’s what makes this sport downright electric. It’s not just the skill or strategy; it’s those jaw-dropping moments when the underdog flips the script and sends shockwaves through the fight world.

In this article, we’re diving deep into MMA’s biggest upsets, the ones that made you jump off the couch screaming “No way!” Whether it was a last-minute knockout or a lopsided decision, these fights prove that in MMA, nothing is impossible. Buckle up, because we’re about to revisit the moments that made us all believers in the underdog.

Why Underdog Stories Are So Powerful in MMA

There’s just something magical about watching someone not expected to win—win. It’s like rooting for David against Goliath, Rocky Balboa running up those steps, or your little cousin finally beating you at FIFA.

In sports, and especially in MMA, underdogs remind us that anything can happen when you have heart, grit, and maybe a perfectly-timed left hook.

But it’s more than just a surprise win. Upsets shake the foundation of the sport. They rewrite rankings, bust betting lines, and even crush legacies. And for fans? They remind us why we watch—because every fight has the potential to be a page in history.

The Elements That Create an MMA Upset

Before we jump into the fights, let’s talk about what makes an upset really stick. It's not just about odds, though those matter. Here's what contributes to a truly shocking MMA moment:

- Mismatch on paper: One fighter is heavily favored based on records, rankings, or hype.
- Unfamiliar styles: Sometimes a dark horse has the perfect game plan or style to neutralize a dominant champ.
- Mental mistakes: Overconfidence, poor preparation, or underestimating the opponent can lead to disaster.
- Fight-ending moment: A sudden KO, a slick submission, or even controversial judging can flip the script.

Now, let’s get to the good stuff.

1. Matt Serra vs Georges St-Pierre – UFC 69

Date: April 7, 2007
Result: Matt Serra def. GSP by TKO (Round 1)

This is the gold standard of MMA upsets.

Matt Serra was coming off The Ultimate Fighter 4, a season designed for UFC veterans to get another title shot. No one—and I mean no one—gave him a real shot at beating GSP. St-Pierre was athletic, technical, durable, and riding high off his win over Matt Hughes. Serra? He was scrappy, but overlooked.

In the first round, Serra rocked GSP with a clean shot, followed by a ruthless barrage of punches that led to a TKO. The MMA world blinked in disbelief.

Why it shocked us: GSP was seen as nearly untouchable at the time. Serra wasn’t just an underdog—he was supposed to be a stepping stone.

2. Holly Holm vs Ronda Rousey – UFC 193

Date: November 14, 2015
Result: Holly Holm def. Ronda Rousey by KO (Round 2)

Ronda Rousey was the face of women’s MMA. She’d been finishing opponents in seconds, and fans were starting to believe she was unbeatable. Then came Holly Holm—quiet, respectful, and a champion boxer making her way into MMA.

Holm put on a striking clinic. She kept her distance, stuffed Rousey’s throws, and landed precise strikes. That head kick in round two? Iconic.

Why it shocked us: Rousey wasn’t just a champion; she was a cultural icon. To watch her go down like that? It was like seeing a superhero fall.

3. Michael Bisping vs Luke Rockhold II – UFC 199

Date: June 4, 2016
Result: Michael Bisping def. Luke Rockhold by KO (Round 1)

Michael Bisping took this fight on just two weeks’ notice. Rockhold had already beaten him once and was looking untouchable.

But Bisping, fighting with nothing to lose, caught Rockhold with a wicked left hook and finished the fight in less than four minutes. Boom. Decade-long UFC veteran finally gets his belt. Telenovela-level drama.

Why it shocked us: Bisping was a career journeyman, a gatekeeper at best. No one thought he’d knock off Rockhold—especially not after already losing to him before.

4. Nate Diaz vs Conor McGregor I – UFC 196

Date: March 5, 2016
Result: Nate Diaz def. Conor McGregor by Submission (Round 2)

Conor McGregor was riding high, fresh off knocking out José Aldo in 13 seconds. He was bold, brash, and unbeatable—or so we thought.

Then Nate Diaz steps in on short notice after Rafael dos Anjos dropped out. Most figured Conor would walk through him. Instead, Diaz weathered the storm, landed clean shots, and submitted McGregor with a rear-naked choke.

Why it shocked us: No one expected McGregor to tap. Not like that. The Irish superstar was humbled, and Diaz became a cult hero overnight.

5. Julianna Peña vs Amanda Nunes – UFC 269

Date: December 11, 2021
Result: Julianna Peña def. Amanda Nunes by Submission (Round 2)

Amanda Nunes wasn’t just dominant—she seemed invincible. Double champ, powerful, technical, experienced. Peña? She was tough, but not in the same league—at least on paper.

But Peña refused to back down. She pressured Nunes, stood toe-to-toe with her in the pocket, and made the champ wilt under pressure. Then came the choke. Nunes tapped, and jaws dropped.

Why it shocked us: No one beats Amanda Nunes. Not that way. Peña didn’t squeak by—she took it to her.

6. Fabricio Werdum vs Fedor Emelianenko – Strikeforce

Date: June 26, 2010
Result: Fabricio Werdum def. Fedor Emelianenko by Submission (Round 1)

Fedor Emelianenko was 31-1 and riding a decade-long unbeaten streak. People thought he was unbeatable. Then he stepped into the cage with Werdum.

Fedor rushed in early and found himself trapped in one of the slickest triangle-armbars ever. He had no choice but to tap.

Why it shocked us: Fedor’s aura of invincibility vanished in under two minutes. The GOAT had fallen.

7. TJ Dillashaw vs Renan Barão – UFC 173

Date: May 24, 2014
Result: TJ Dillashaw def. Renan Barão by TKO (Round 5)

Barão hadn’t lost in nine years. He was seen as a monster at 135 pounds. Dillashaw? He was a last-minute replacement who wasn't even supposed to be in the title mix yet.

But Dillashaw dominated from the opening bell. He outclassed Barão in every round and finished him in the fifth. It was a masterclass.

Why it shocked us: No one expected such a one-sided beatdown—from a guy with zero title-fight experience.

The Psychology of a Fighter: Why Underdogs Rise

Sometimes, not having the spotlight is the biggest advantage of all. Underdogs don’t carry the pressure of defending a belt or living up to hype. They’re free to fight without being paralyzed by expectations.

That freedom? It’s dangerous.

Also, underdogs often study their opponents deeply, prepare like maniacs, and walk into the cage with a “nothing to lose” attitude. And in a game where one mistake can cost you everything, that mindset can flip the odds quickly.

How The MMA World Reacts to Upsets

Upsets shake things up. Fans go nuts, sportsbooks lose millions, and suddenly everyone’s debating whether the “GOAT” conversation needs reworking.

Social media blows up, rematches get booked, and narratives start flying. The beauty of an upset is that it invites chaos—and chaos sells.

Lessons from the Greatest MMA Upsets

Here’s what all these upsets teach us:

- Never count anyone out – That 10-to-1 underdog? Might just be your next champ.
- Styles make fights – Even legends have kryptonite.
- Composure is everything – Panic costs fights.
- Arrogance is risky – Overlooking a hungry fighter = bad idea.
- The sport is evolving – Today’s underdog might be tomorrow’s superstar.

If there’s one thing MMA fans should have by now, it’s humility. Because just when you think you’ve seen it all, the sport throws you a curveball that reminds you why you fell in love with it in the first place.

Why We Love These Moments

You may love a dominant champ, but we all live for the upset. It’s the reminder that heart trumps hype, that willpower can beat talent, and that even giants fall.

Underdog stories are what keep MMA thrilling. They’re not just stories of surprise—they’re stories of perseverance, grit, and the beautiful unpredictability of combat sports.

So next time there’s a “sure thing,” remember: in MMA, there’s no such thing.