This Saturday at UFC 133, Tito Ortiz will headline the main event in a bout where few believe he can win, but which many would not be surprised by should he pull off the upset.
Originally set to square off against newly crowned UFC Light Heavyweight Champion Jon Jones, Jones was forced out of the fight due to a lingering hand injury, forcing Rashad Evans to find a new opponent.
Jones was then replaced by up-and-coming prospect Phil Davis; that was, until Davis was forced out with an injury of his own.
Now, Evans will be engaging in a rematch of a 2007 bout at UFC 73 against former champ Tito Ortiz.
The fight ended in a draw and left a sour taste in Evans' mouth, but even more so for Ortiz, who would have most likely won the match had he not been deducted a point for holding the fence.
At the time, Ortiz was coming off the loss of his light heavyweight title to Chuck Liddell while Evans was on the brink of transforming into the superstar he would eventually become.
Fast forward to this Saturday and now the roles are reversed, with Evans now in a relatively stagnant position following his absence for over a year and Ortiz riding high off the momentum of his first-round submission victory over Ryan Bader at UFC 132.
Underdog or not, its hard not to count out Ortiz, especially after defeating a youngster in Bader, who many believe will become an eventual title contender.
And he doesn't seem to be the only fighter hoping to beat the odds this Saturday, as middleweight Yoshihiro Akiyama hopes to avoid a third straight loss while welterweight Mike Pyle plans to halt a young lion in Rory MacDonald from surging up the divisional rankings.
In the birthplace of the sports cinema's most famous underdog, Rocky Balboa, the biggest stories coming out of UFC 133 might end up being a few dramatic upsets.
Here are five underdogs going into UFC 133 that would pull off an upset this Saturday.