LOS ANGELES -- The USC football team had barely opened fall camp when starting quarterback Mark Sanchez put his status for the opening game at Virginia in doubt by dislocating a kneecap. Now the status of another potential backfield starter is in doubt 11 days before Charlottesville.

Redshirt sophomore C.J. Gable, expected to carry the load at tailback this fall alongside junior Stafon Johnson, stayed down after being tackled during team drills.

"Sure, he's hurt," said USC coach Pete Carroll. "I don't know how bad, but it was very awkward the way he hit the ground. We'll just have to wait and see."

Trainers seemed to be attending to Gable's knee and ankle.

"He felt it in his hip," said Carroll. "It got kind of jammed into the ground. But they're looking at his knee and his ankle as well.

Gable started USC's first two games of 2007 before suffering a season-ending abdomen injury. He rushed for 434 yards and four touchdowns as a freshman in 2006.

"He's a good football player," said Carroll. "We love the way C.J. plays. He can do everything. He run, catch the football and he's a great pass (protection) guy. So that affects us. He's a dynamic player that is tough and we love him."