Everyone loves the element of surprise in sports; it gives us a reason to watch. If we knew who would win, there'd be no point in watching.
In MMA, though, upsets are more likely to occur than in any other sport.
People are more inclined to believe in, say, Stephan Bonnar's chances against Anderson Silva at UFC 153, due to the fighter always having a puncher's chance. The same isn't true of college football, where a small minority are going to believe Sam Houston State can beat the University of Texas.
Here are the ten most shocking upsets in MMA, based on what it meant to MMA history, titles on the line and winning streaks.
This fight has been the biggest fight so far in the Zuffa-run Strikeforce.
You had Dan Henderson, who was the former Pride middleweight and light heavyweight and the current Strikeforce champion.
Then you had Fedor, the former Pride heavyweight champion, who had the longest winning streak in MMA history until he lost to Fabricio Werdum in June of 2011.
This was a fight people never had expected to see, considering Henderson went from middleweight to come back to light heavyweight and win the Strikeforce Light Heavyweight title from Rafael "Feijao" Cavalcante in March of 2011.
This fight was considered a mismatch with Henderson, who people thought should have been fighting as a middleweight, facing quite arguably the greatest heavyweight of all time.
But in a historical aspect, it was two of the greatest fighters of all time squaring off.
July 30, 2011, at the Sears Center in Hoffman Estates, IL, right outside of Chicago. Henderson weighed in at 207 pounds for the heavyweight tilt.
It was a brilliant back-and-forth with a great closing sequence. Emelianenko hit Henderson with one of his looping hooks, then got on top of Henderson on the ground and hit him a couple of times.
Henderson, though, saw a hole. He hit Fedor, and Emelianenko was out with referee Herb Dean stopping the fight at 4:12 of Round 1.
A bona fide middleweight stopped arguably the greatest heavyweight in MMA history.
This was a return for the first-ever UFC Lightweight Champion in Pulver, who left in 2002 after defeating BJ Penn at UFC 35.
Joe Lauzon was making his UFC debut with a 13-3 record, but those fights were all on the regional circuit.
Pulver and Lauzon squared off at UFC 63 with Pulver being a 7-1 favorite. The fight was meant to showcase the return of Pulver, but Lauzon would have no part of it.
Forty-seven seconds into the fight, Pulver was out for the count and staring up at the lights.
A former UFC heavyweight champion getting knocked out by a 48-year-old former boxing heavyweight champion in under 10 seconds isn't supposed to happen.
But that is exactly what happened on June 13, 2009, at Adrenaline III: Bragging Rights, when Tim Sylvia took on Ray Mercer.
There were a lot of legal issues going into the fight. It was originally promoted as a boxing event, but was changed to an MMA fight due to regulation challenges from the Association of Boxing Commissions.
At the beginning of the fight, Sylvia missed an inside leg kick, and Mercer threw an overhand right to knock him out.
Ten seconds was all it took for a former world champion boxer at the age of 48 to finish a former UFC heavyweight champion.
Royce Gracie, by the time we got into the 21st century, was considered the greatest fighter of all time.
Gracie won three of the first four UFC tournaments before taking a superfight with Ken Shamrock, which was fought to a draw. After that fight, Gracie left the UFC and wasn't seen again for five years until he fought at Pride 2000 Grand Prix and defeated Nobuhiko Takada.
Kazushi Sakuraba was a former professional wrestler who was a submission expert from catch wrestling.
No one gave the former pro wrestler a chance against the man a lot of people thought was unbeatable.
The fight took place at Pride Grand Prix Opening Round on May 1, 2000.
Early in the fight, Gracie got caught in a couple of kneebar attempts by Sakuraba. It looked like Gracie was in big trouble as the fight progressed.
Gracie was getting leg kicked to death, but wouldn’t quit. Neither man looked like they were any closer to ending the fight than they had been 90 minutes prior.
Finally Gracie could no longer stand up, after suffering a broken femur bone, and his brother threw in the towel to end the fight.
Some people are going to wonder why this fight even belongs on a list like this.
Kimbo Slice was a You Tube sensation with videos showing him beating up people in the Miami, Florida, area. Elite XC saw the exposure that Slice was getting and signed him to a lucrative contract.
Slice made his debut for the organization in November of 2007 and defeated Bo Cantrell. Before the Petruzelli fight, Slice defeated Tank Abbott and James Thompson, with the Thompson fight being the first MMA card on CBS.
Petruzelli was a last-minute replacement for Ken Shamrock, who got cut warming up for the fight.
The fight lasted all of 0:14, as a right hand by Petruzelli put Slice onto dream street with the fight being stopped.
Not only did Petruzelli knock out Kimbo Slice, he knocked out Elite XC as well.
A few days after the fight, Petruzelli called Monsters in the Morning, a radio show in Orlando, Florida, and claimed that he was paid extra money and told by Elite XC officials to not take Slice down. Elite XC denied the allegations, but folded soon after.
You think of BJ Penn and Matt Hughes, and you think of two legends and two of the greatest of all time.
A lot of people only remember their facing off when Penn knocked out Hughes at UFC 123 in November of 2010.
But they fought two previous bouts.
Hughes beat Penn to win the welterweight championship at UFC 63 in September of 2006.
The first time they fought, though, was at UFC 46 on January 31, 2004. Penn was making his return to the UFC after leaving the organization after his draw against Caol Uno at UFC 41.
But this time, Penn was returning as a welterweight. The UFC had suspended the lightweight division at that time, which was the reason for Penn fighting at 170.
Hughes was the heavy favorite heading into the fight. After winning the title over Carlos Newton at UFC 38, he had made five straight title defenses before the showdown with Penn.
The fight didn't last long, as Penn was able to take Hughes' back. At 4:39 into the first round, Hughes submitted to rear naked choke and Penn became the UFC welterweight champion.
This was a fight that perplexed fans.
A lot of fans had felt that Grey Maynard deserved the title shot more than Edgar. But after Edgar submitted Matt Veach at The Ultimate Fighter Season 10 finale and Maynard defeated Nate Diaz by split decision at Ultimate Fight Night 10, the UFC decided to give the shot to Edgar.
After defending the lightweight strap three straight times and winning in decisive fashion, Penn was being called the greatest lightweight of all time.
Penn walked into his UFC 112 bout with Edgar on April 10, 2010 as a 7-to-1 favorite. Edgar used his boxing for five rounds with constant head movement, which confused the champion for 25 minutes.
Penn was never able to corner Edgar and impose his will with strikes or ground and pound. Edgar never stopped moving. He confused Penn with great movement, precision striking, and takedowns to take the UFC lightweight title by unanimous decision
Randy Couture was enjoying retirement in 2006 and the early part of 2007.
He had lost the trilogy fight to Chuck Liddell at UFC 57 in 2006, and had announced his retirement after the fight. Couture was doing some broadcasting work for the UFC and was very happy in retirement.
Sylvia was on a six-fight winning streak and defended the UFC heavyweight title on two occasions.
The heavyweight division was in flux with no viable contenders. The UFC lured Couture out of retirement to take a fight with Sylvia, which was to take place at UFC 68 on March 3, 2007.
People thought this was an obvious mismatch. Couture was 6'1" while Sylvia was 6'8" with a five-inch reach advantage. Not to mention Couture was 43 years old while Sylvia was 31.
The crowd in the Nationwide Arena was electric as both guys came into the cage, cheering for Couture. In the opening moments of the fight, Couture dropped Sylvia with an overhand right to set the tone for the rest of the fight.
Couture dominated all five rounds to do the impossible: win the UFC heavyweight title at the age of 43.
No person is invincible, no matter how great they are.
All the greats in MMA have lost, including Royce Gracie, Matt Hughes, Anderson Silva and Georges St.Pierre to name just a few.
MMA fans around the world thought Fedor Emelianenko would never lose again. The only loss for Emelianenko at that time was in his fourth fight, when he lost to Tsuyoshi Kohsaka at Rings: King of Kings 2000 Block B, when the fight was stopped 17 seconds into the fight due to a cut to Emelianenko's head.
Footage showed that the cut was caused by a punch where Kohsaka's elbow struck Emelianenko's head. Elbow strikes were illegal under RINGS rules unless the striker was wearing elbow pads, which Kohsaka was not.
A lot of people really don't consider that a loss for Emelianenko, regardless of the official record.
Fedor had been the Pride Heavyweight Champion and the 2004 Pride Heavyweight Grand Prix Champion before Pride folded.
After Pride folded, Fedor went on to fight under the Bodog and Affliction banner before signing with Strikeforce in 2009. After defeating Brett Rogers in November of '09, Fedor was scheduled to fight Fabricio Werdum on June 26, 2010.
Werdum, who had also fought in Pride from 2004-2006 with a record of 5-2, headed into the UFC in 2007. There, he lost a unanimous decision fight against former heavyweight champion Andrei Arlovski at UFC 70.
Werdum complied a robust 2-2 record in the UFC and was released after his knockout loss to now heavyweight champion Junior Dos Santos at UFC 90 in October of 2008.
Going into this fight, no one really thought Werdum had a chance. Fedor was on a 28-fight winning streak. People were targeting a fight between Emelianenko and then Strikeforce heavyweight champion Alistair Overeem.
To start the fight, Fedor knocked Werdum down with a combination of hard punches. But then he made a huge blunder, going to the ground with Werdum, who was regarded as the best in the MMA at Brazilian jiu jitsu.
Werdum put Fedor in a triangle armbar and Fedor tapped out 69 seconds into the fight.
It was considered one of the biggest upsets in MMA history.
Emelianenko lost two more fights in a row before getting released by Strikeforce last year. Fedor went on to win three more fights for M-1 Global and Dream before retiring after his win over Pedro Rizzo in June.
Werdum used the win to springboard into the elite in the heavyweight division and will be coaching TUF Brazil starting in early 2013.
Matt Serra defines the term underdog.
An underdog is someone that is expected to lose a contest or struggle. People that are 5'6" and weigh 170 pounds are not supposed to be fighters. They should be working 9-5 jobs.
Serra was on The Ultimate Fighter Season 4, which was the comeback season. The season was based on guys who had fought in the UFC before, but never won a UFC title. That season's fighters were made up of middleweights and welterweights.
Serra defeated Pete Spratt and Shonie Carter to advance to the finals. In the final, Serra defeated Chris Lytle by split decision to win the season and get a crack at UFC welterweight champion Georges St-Pierre.
St-Pierre had just defeated Matt Hughes at UFC 65 to win the welterweight title, and was 13-1 heading into the Serra fight at UFC 69.
Besides the better record going into the fight, St-Pierre had a four-inch height advantage and an eight-inch reach advantage.
About three minutes into the fight, Serra connected with a right hook that hit St-Pierre behind the ear and sent the champion stumbling. Serra finished it off and became the champion.
That was, and still is, the biggest shocker in MMA history.