Sanchez looks good in drills

It was supposed to serve as the final proving ground for USC quarterbacks Aaron Corp and Mitch Mustain in their competition to possibly replace injured starter Mark Sanchez.

It still might, but today’s scrimmage at the Coliseum looks more like a stage to decide who could be Sanchez’s backup.

On Wednesday, Sanchez took another step toward returning for the Aug. 30 opener at Virginia, participating in 7-on-7 passing drills for the first time since suffering a dislocated left kneecap Aug. 8. If the junior has no setbacks, he will participate in all drills next week and probably start the opener.

“He looked terrific,” Coach Pete Carroll said.

Sanchez said he was “a little rusty” and his timing was a bit off. But his leg felt fine.

“I didn’t even think twice about it,” he said.

Sanchez moved well and threw the ball with velocity. Maybe too much. His first pass to running back Joe McKnight conjured images of a Boston Red Sox reliever, according to offensive coordinator Steve Sarkisian.

“He threw like Jonathan Papelbon, a 99-mile-an-hour fastball -- and Joe has two [injured] fingers,” Sarkisian said.

Sanchez will be held out of the scrimmage, but he took first-team snaps during the Trojans’ walk-through Wednesday afternoon.

Corp took first-team snaps during the morning practice and will start the scrimmage. Corp’s and Mustain’s performances could go a long way toward deciding who would be No. 1 if Sanchez can’t play against Virginia.

“We’re going to look closely at it,” Sarkisian said. “We need to assess how they can manage the football for us.”

Comeback kid

Running back C.J. Gable, who suffered hip and ankle injuries Tuesday when he was tackled during a scrimmage drill, moved without crutches after the afternoon walkthrough. Players and coaches were not available to the media.

A school official said Gable suffered a hip strain and ankle sprain, but added that team medical personnel were still awaiting final results of an MRI exam.

Gable’s availability for the opener is uncertain. Asked how the loss of the former Sylmar High star could affect the Trojans, Sarkisian did not hesitate.

“We lose our most complete running back,” Sarkisian said. “The guy that can do all three phases of the game: can run the ball, can catch the ball and can pass protect.

“A lot of the other guys can do two of the three things. I don’t know if any one of them have all three facets.”

Gable started the 2006 and 2007 season openers. He played three games last season before having season-ending abdominal surgery that forced him to redshirt.

“We have guys that can get the job done,” Carroll said, “but . . . he’s the best all-around guy at all the things we do.”

Junior Allen Bradford, who sat out Tuesday because of hip soreness, returned to practice.

Injury report

USC’s defense, already down starting cornerback Cary Harris (dislocated shoulder), also could be without tackle Fili Moala today.

Moala sat out practice because of back spasms. The senior said he had been experiencing back problems for a month.

Oft-injured linebacker Brian Cushing emerged from the locker room after the morning practice with a soft cast on his left wrist. “It’s just a sprain,” he said. “It’s nothing.”

Quick kicks

Today’s scrimmage begins at 3:30 p.m. The event is open to the public and admission is free. . . . Cornerback Shareece Wright did not practice because of groin soreness, according to Carroll. . . . Former USC quarterback Todd Marinovich attended practice.

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gary.klein@latimes.com