ANN ARBOR, Mich. -- Michigan cornerback Troy Woolfolk left the Wolverines' game against San Diego State with a lower body injury in the second quarter and has not returned.
Woolfolk, one of No. 22 Michigan's starting cornerbacks, missed all of the 2010 season with an ankle injury. Michigan's radio broadcast is reporting Woolfolk injured an ankle.
After injuring the ankle, Woolfolk slammed his helmet to the ground while being attended to by trainers on the bench. He eventually stood and tried to stretch out his legs.
Entering the game, Woolfolk had made five tackles this season -- but also missed part of the Western Michigan and Notre Dame games with varying injuries suffered during play.
Sophomore cornerback Courtney Avery replaced Woolfolk. Michigan's defense also shut an opponent out in the first half for the first time since Sept. 5, 2009, against Western Michigan.
After Michigan's 28-7 win over the Aztecs, Wolverines coach Brady Hoke said Woolfolk injured his left ankle -- the same one he injured in the season opener against Western Michigan.
Hoke listed him as "day to day."
"If I know Troy," Hoke said. "He'll come out tomorrow and do everything that we need for him to do."
Michael Rothstein covers University of Michigan sports for WolverineNation.