UFC 155: Junior Dos Santos vs. Cain Velasquez – December 12,2012
Junior dos Santos vs. Cain Velasquez rematch was already expected since May 26, 2012 at UFC 146, in which dos Santos defended his belt against Frank Mir and Velasquez defeated Antonio Silva. Velasquez and dos Santos have already fought each other on November 12, 2011 at UFC on Fox: Velasquez vs. dos Santos, where dos Santos won his title via knockout in the very first round. Alistair Overeem, former DREAM and Strikeforce champion, is expected to face the winner of this bout. He was 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). He tested positive for elevated levels of testosterone with a ratio of 10-to-1, over the allowed ratio rate of 6-to-1
Chael Sonnen was expected to face Forrest Griffin at this event. 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.