USC quarterbacks have an off day

Mark Sanchez, Mitch Mustain and Aaron Corp enjoyed some shining moments during USC’s first three spring practice workouts, but the trio also hit a bit of a collective wall Friday.

“All three of the guys threw some balls that weren’t as sharp,” Coach Pete Carroll said. “It’s the first day in pads and they could feel the rush a little bit more. I think that takes a little bit to get used to.

“I’m not worried about it all.”

Cornerback Cary Harris and safety Kevin Ellison combined to intercept a pass thrown by Sanchez.

Mustain had one pass tipped and another knocked down by a defensive lineman on successive plays.

Corp also struggled at times.

“It wasn’t my best day,” he said.

So, it’s status quo in the competition to find a successor to two-year starter John David Booty. Sanchez, a junior who started three games last season, remains the front-runner.

When asked who was leading, Mustain did not hesitate.

“Mark still is; he’s doing a good job,” Mustain said. “Aaron and I are playing catch-up.”

Carroll agreed.

“Everything is just kind of where you think it would be,” he said. “There is no opportunity to make an evaluation yet. It would be a mistake to even try to do that.”

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Cornerback Kevin Thomas pronounced himself fit after testing his surgically repaired left shoulder in full contact drills for the first time.

Thomas started the 2006 opener at Arkansas but missed most of the season because of an ankle sprain and broken foot. He redshirted last season after having shoulder surgery in the spring.

“I did all the hitting drills and tried to focus on using my left shoulder – I felt no weakness,” Thomas said. “I’m taking all the contact and it feels good.”

Thomas intends to regain a starting spot in a competition with senior Harris, junior Shareece Wright and senior Josh Pinkard.

“It feels like I’m picking up where I left off,” Thomas said.

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The practice was conducted before hundreds of youth, high school and college football coaches who are attending a clinic that continues today. USC players are off today. They resume practice Sunday with a workout that is open to the public… . Carroll said the Trojans would probably scrimmage late next week… . Tailback Allen Bradford continued his dynamic play with a 35-yard touchdown run during team drills… . Linebacker Rey Maualuga provided the biggest hit of the day when he brought down running back C.J. Gable.

gary.klein@latimes.com