Mixed martial arts is one of the most unpredictable sports in the world, almost or more so than betting. If you are one of the gamblers who enjoys online casino bonus offers, you surely have that last point quite clear.
The reality is that many fighters began their career in mixed martial arts as the “underdogs” in the eyes of the public. However, they demonstrated that they had a lot to give and, with 2025 nearly over, they have everything to show the world. Do you want to know who they are? We look at some of the underdog fighters who shocked the MMA world.
Underdog Fighters: The charm that lies behind MMA and captivates the world
When it comes to going for something new in sports, we can expect no less from mixed martial arts. This contact activity is one of the most versatile sports due to the number of significant names that have emerged throughout history.
MMA fans always have one of these life-changing victories up their sleeve, and the truth is, it’s for a good reason. The excitement of this sport is not limited to physical contact, but also to the multiple mental and, of course, emotional conditions that each of these athletes develops to achieve their goals. The key that makes MMA something unique is that many names who entered the octagon as irrelevant figures left it as legends.
Matt Serra Stuns GSP
Matt Serra
One of the most surprising names in the entire history of MMA is Matt Serra. This American fighter surprisingly took the UFC welterweight championship in 2007 against Georges St-Pierre, who was poised to be the undisputed winner at the time. GSP is one of the best fighters of all time.
The most interesting part of this victory was not just the KO, but what it meant for Serra’s career, leading to a hundred-thousand-dollar contract and highly important sponsorships.
Why it was such an upset
- Serra earned the title shot by winning The Ultimate Fighter 4, coming in as a veteran seen more as a grappler than a knockout threat.
- St-Pierre was viewed as the future of the division, on a dominant run with wins over top contenders and was reportedly as high as a -1300 favorite with some sportsbooks.
What happened in the fight
- At UFC 69 in Houston, Serra stunned St-Pierre with a looping right hand behind the ear in round one, then swarmed with punches until a TKO stoppage at 3:25 of the first round.
- The loss later became a key turning point in GSP’s career, after which he changed to a more risk-averse, control-heavy style and never lost again before retiring.
Holly Holm Shocks The Queen of MMA Ronda Rousey
Holly Holm is one of the leading boxers in MMA, but this was not always the case. Her career began with a low profile, though without underestimating her talent, which was always clear and manifest. Her titles in the welterweight division are several and she gathers other local and international recognitions. One of her best moments was in 2008 when she defeated Mary Jo Sanders, who was the champion at the time. This victory secured her belts from 140 to 154 pounds. But that’s not the one we’ll remember. That happened against the most famous female fighter of all time, Ronda Rousey.
- Holm was considered a massive underdog, with Rousey unbeaten and a dominant champion at the time.
- Holm controlled the bout with her striking and successfully defended against Rousey’s signature takedown attempts, winning by a stunning head kick knockout in the second round.
- This victory ended Rousey’s undefeated streak and her reign as champion, making it one of the most shocking upsets in UFC and combat sports history.
The fight is frequently cited among the biggest upsets ever in the UFC and in all of sports, as Rousey was seen as unbeatable before that night. Holm’s win is remembered as an iconic moment for women’s MMA and changed the landscape of the division.
Michael Bisping Takes Down Luke Rockhold on Short Notice
Michael Bisping has not been one of the most popular names in mixed martial arts, however, he was a key piece in important moments of the sport. In 2008, he won his first fight by KO when he faced Charles McCarthy at UFC 83. He had a second fight the same year, but against Jason Day, whom he also defeated by KO.
Michael Bisping’s biggest upset though was his knockout victory over Luke Rockhold at UFC 199, where he captured the UFC Middleweight Championship as a +500 underdog. He took the fight on short notice and defeated Rockhold, who had previously beaten him and was widely considered the heavy favorite.
- Bisping only received the title shot because the original challenger, Chris Weidman, withdrew due to injury, making Bisping a late replacement.
- In their previous encounter, Rockhold had convincingly defeated Bisping, which further added to the perception that Bisping was unlikely to win.
- Despite being overlooked by most analysts and oddsmakers, Bisping managed to knock out Rockhold in the first round with a striking combination, securing what is considered one of the biggest upsets in UFC title fight history.
Julianna Peña Shocks The Lioness, Amanda Nunes
Julianna Peña is an excellent mixed martial artist from the United States and one of the most current names in the spotlight, although she has gained ground in this sport step by step. Her beginnings were as an amateur and she managed to debut in MMA as a professional until 2009. Among her most recent championships is the UFC Women’s Bantamweight, of which she is the current champion.
Julianna Peña’s biggest upset was her victory over Amanda Nunes at UFC 269 in December 2021, when Peña submitted Nunes in the second round as a 6.5-to-1 betting underdog, making it one of the greatest upsets in UFC title fight history, if not number one. Amanda Nunes is hailed as the most dominant fighter in MMA history, so reflecting on the upset is made more spectacular. The two fought again at UFC 277 when Nunes defeated Pena. But that does nothing to tarnish the memorable upset in their first bout.
The Fight Details
- Peña defeated Nunes with a rear-naked choke submission in the second round.
- Nunes was widely regarded as the most dominant women’s MMA fighter at the time.
- Peña’s win shocked the MMA world and is frequently called the greatest upset in the history of women’s MMA and among the biggest upsets overall in UFC.
- Peña became the UFC women’s bantamweight champion after this fight.
MMA, the odds, and the surprises that give the sport its “special touch”
The reality about MMA is that, compared to other sports, this activity, which is also an art, is full of surprises and situations that can change from one moment to the next. There are many people who follow mixed martial arts as a sport of great interest and who expect any last-minute change in the octagon.
The MMA victories of these less prominent fighters (for some) not only represent numbers. Beyond this, they imply a direct connection with the fans who long to see new faces. MMA is not just about fights; they are also epic tales of personal overcoming. That is why these moments remain etched in the collective memory: they are the stories that best capture the soul of the octagon.
Without a doubt, all these athletes who make a life in this activity generate a generational impact that does not stay within the martial art, but goes much further. At the end of the day, they are a clear example that it is possible for your name not to be the most prominent at some point, but that when you least expect it, your opportunity to make yourself known arrives.
main image credit: IMAGO / ZUMA Press Wire