5 of the biggest upsets in UFC history

2. Matt Serra def. Georges St Pierre - UFC 69

One might make the argument that Matt Serra should have never been a UFC champion. And it may be a fair argument, but guess what? He was. And he did it in historical fashion with one of the earliest examples of an insane upset.

Unlike some of the other names on this list, Serra didn't earn his title shot with a major winning streak or by stepping up on short notice. He didn't even win a traditional title eliminator. He earned the title shot...by winning a reality show.

Subtitled "The Comeback," the fourth season of The Ultimate Fighter featured 16 UFC fighters who had yet to win a UFC championship. Serra, who was 4-4 in the UFC prior to this and mainly fought at 155 pounds, participated in the welterweight portion of the competition, defeating Pete Spratt, Shonie Carter, and Chris Lytle to win the tournament and earn a title shot against Georges St Pierre.

There were a variety of reasons many felt GSP vs. Serra was a mismatch. Plenty felt GSP — who won the UFC's 170-pound belt from Matt Hughes one week after Serra's TUF win — was just the all-around better fighter. Plenty felt Lytle should have been given the judges' nod in the finale fight. Fellow TUF season 4 winner Travis Lutter had blown his middleweight title shot not long prior after missing weight. The odds seemed stacked against Serra in this one.

But Serra proved that odds are just numbers. And in one of the most jaw-dropping performances ever seen in MMA, Serra rocked and dropped GSP, finishing him in under four minutes, to become UFC welterweight champion.

While Serra's run with the belt only lasted a year, dropping the title back to GSP at UFC 83 with zero successful title defenses and starting GSP's over five-year run with the strap, Serra left a legacy in the Octagon with that one superstar performance in April 2007. He's done even better for himself in retirement as a personality and with the Serra-Longo Fight Team.