Running back Gable is injured in practice

USC’s backfield, already in flux with quarterback Mark Sanchez coming back from a knee injury, sustained another blow Tuesday when running back C.J. Gable suffered hip and ankle injuries.

Gable, a redshirt sophomore who started the 2006 and 2007 openers, sustained a sprained left hip and ankle when he was tackled during a scrimmage drill.

“It was real awkward the way he hit the ground,” Coach Pete Carroll said.

Gable lay on his back for several minutes before he was assisted off the field by team trainers. He was carted to the locker room and examined by team physician James Tibone.

“I think his hip is the worst part,” said Tibone, who declined to comment about how long Gable might be sidelined.

Gable redshirted in 2007 after having abdominal surgery following the third game.

He was on crutches Tuesday when he emerged from the locker room.

“I don’t feel like talking,” Gable told reporters.

Despite Gable’s injuries, running backs coach Todd McNair remained optimistic as the Trojans prepare for the Aug. 30 opener at Virginia.

“There’s always a worry when one of my guys goes down,” he said. “But we’ve got a lot of depth.”

That depth, however, is thinning.

Junior Stafon Johnson and redshirt freshman Broderick Green are the only tailbacks without apparent health issues.

Junior Allen Bradford, who struggled at times with a hip injury last season, sat out Tuesday’s practice because of hip soreness. He said he would try to return today but acknowledged he could be out longer.

Sophomore Joe McKnight practiced, but continues to nurse right elbow soreness and finger injuries that have caused him to play almost one-handed.

Freshman Marc Tyler returned to practice but has a sore left ankle.

Sanchez’s snaps

Sanchez was not in pads, but he took snaps with the first-team offense during pre-practice drills and then threw passes to receivers.

Offensive coordinator Steve Sarkisian said that barring setbacks, Sanchez could be in the starting lineup at Virginia.

“From what I saw today, he’s on pace,” Sarkisian said.

Sanchez worked off to the side when the Trojans went through their pre-stretching drills, but just as he did Aug. 8 when he suffered a dislocated left kneecap, he threw a pass to Clay Matthews as the Trojans spread out to stretch as a team. Sanchez then went through a series of drills with the other quarterbacks.

“I felt in rhythm, my arm strength felt fine,” Sanchez said.

Tibone examined Sanchez immediately after practice and said, “He’s looking really good.”

Meanwhile, in the competition to possibly start in place of Sanchez, redshirt freshman Aaron Corp took nearly all of the first-team snaps in full-team drills.

“When you’re in there you have to kind of take advantage of it,” Corp said. “If you’re going to keep making plays you’re going to stay there. If you mess up the other guy is going to go in.”

Thursday’s mock game at the Coliseum is expected to be a final exam of sorts for Corp and Mitch Mustain.

Game management is a top priority for Sarkisian.

Quick kicks

Safety Kevin Ellison was given most of the practice off to rest, Carroll said. . . . The Trojans will practice today at 10:30 a.m. and then will have an afternoon walk-through before traveling to a downtown hotel in preparation for Thursday’s mock game. The game is open to the public.

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gary.klein@latimes.com

david.wharton@latimes.com