UFC Bantamweight champion Dominick Cruz suffered another big setback after he underwent his second major knee operation that can keep him out for up to a year.

MMA website MMAJunkie.com broke the story about the second knee surgery earlier today, saying that his body rejected the cadaver ACL placed in his left knee earlier this year during the first surgery.

The first surgery prevented Cruz from fighting Urijah Faber after the two coached The Ultimate Fighter. Faber eventually fought Renan Barao for the interim Bantamweight title which Barao ended up winning.

Cruz holds an MMA record of 19-1, with his only defeated coming to Urijah Faber in March 2007. He last fought Demetrious “Mighty Mouse” Johnson in October 2011 in Washington.