Lesnar was advertised as a coach of "The Ultimate Fighter Season 13", opposite Junior dos Santos, with the two expected to fight on June 11 at UFC 131, but he was struck with another bout of diverticulitis and had to withdraw from the fight on May 12. He was replaced by Shane Carwin, who ended up losing against dos Santos. Lesnar underwent surgery on May 27 to help battle his problems with diverticulitis. Dana White said that he had a 12-inch piece of his colon removed.