Polamalu Will Sit Out Scrimmage

Troy Polamalu, USC’s All-American safety, did not practice Friday and will not participate in today’s scrimmage after suffering a mild concussion when he tackled running back Justin Fargas on Thursday.

“This is the right time to take extra precautions,” Coach Pete Carroll said.

Polamalu, who sat out four games during his freshman season because of a concussion, underwent a CT scan and spent Thursday night in a hospital under observation.

“They said everything was fine,” Polamalu said. “I wasn’t worried about it.”

Sophomore Jason Leach worked with the first unit in Polamalu’s absence.

Carroll said the Trojans would run about 50 plays today.

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With fifth-year senior Carson Palmer entrenched as the starting quarterback, the battle to become his backup is heating up.

Redshirt sophomore Matt Cassel and redshirt freshman Matt Leinart will see significant action during today’s scrimmage.

“It’s getting down to crunch time on figuring it out,” Carroll said.

On Thursday, Carroll cut back Palmer’s workload to give Cassel and Leinart more snaps, and on Friday both got work.

“The scrimmage is not going to be that much different than practice,” Cassel said. “As a quarterback, you have to go out and execute and move the chains.”

Leinart looks forward to another chance to compete.

“You know you have to perform [in a scrimmage] because you know this is what the coaches look for,” he said.

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Running back Sultan McCullough, nursing a sore left hamstring, will not participate today.

“We’re going to give him a couple days and make sure this isn’t going to linger,” Carroll said.

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Junior cornerback Marcell Allmond remained in the hospital for a third night for treatment of an infected right knee.

Carroll said Kevin Arbet will start at left cornerback.

Junior college transfer Ronald Nunn and freshman Justin Wyatt continue to push Darrell Rideaux on the right side.

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Senior cornerback Miguel Fletcher did not attend afternoon practice and is mulling his future in the program, Carroll said.... Wide receiver D. Hale will miss the scrimmage because of a sore ankle.... Senior fullback Chad Pierson injured his left hamstring running a pass route and might sit out.... Freshman punter Tom Malone did not kick for the second day in a row because of a sore right hamstring. He is expected to kick today.... Linebacker Chris Prosser remained sidelined while recovering from a hard shot to the head sustained earlier this week.