UCLA's Kenyon Coleman, one of the nation's top defensive linemen, had surgery on his left knee Tuesday and is expected to be out 4-6 weeks.
Doctors removed a torn portion of the cartilage in his injured knee during the operation.
Coleman, a 6-foot-6, 280-pound senior, was hurt early in Saturday's 23-20 victory over Michigan.
In addition, the Bruins will be without fullback Matt Stanley for a minimum of four weeks. Stanley dislocated his right shoulder early in the Michigan game.
Meanwhile, Stanford quarterback Randy Fasani probably will miss the rest of the season because of cartilage and ligament damage in his left knee suffered Saturday against Texas. A final determination will come after he undergoes arthroscopic surgery Sept. 29.