UFC 155: dos Santos vs. Velasquez 2 was a mixed martial arts event held by the Ultimate Fighting Championship on December 29, 2012, at the MGM Grand Garden Arena in Las Vegas, Nevada.

Alistair Overeem, former DREAM and Strikeforce champion, was expected to face the winner of this bout.

He was originally expected to face dos Santos for the title at UFC 146; however, on April 4, 2012, Overeem was revealed to have failed his pre-fight drug test by the Nevada State Athletic Commission (NSAC).

However, Sonnen was pulled from the fight to coach the seventeenth season of The Ultimate Fighter opposite UFC Light Heavyweight champion Jon Jones and was replaced by Phil Davis.

[6] Griffin was then forced out of the bout with a knee injury and Davis was pulled from the card altogether.