Center Ryan Kalil, the most experienced member of USC's offensive line, did not practice Thursday because of concussive symptoms, but Coach Pete Carroll said the senior would play for the fourth-ranked Trojans on Saturday against 19th-ranked Nebraska.
Kalil, a team captain who was an All-Pacific 10 Conference selection last season, was hit in the head during a scrimmage drill near the end of practice Wednesday.
Kalil watched Thursday's workout, then ran through the gate at its conclusion and sprinted away from reporters to the locker room.
Asked if Kalil had a concussion, Carroll said, "He doesn't have one today. He got hit in the head, but he doesn't have a concussion that lasted through today, so he's OK. He's clear."
Carroll said the 6-foot-3, 285-pound Kalil was held out as a precaution.
"They wanted him to be careful and make sure he's all right -- with flying colors he passed all his tests," Carroll said.
Kalil is one of the Trojans' most important players because he anchors a line that features three players making only their second starts. Quarterback John David Booty also has started only one game.
Third-year sophomore Jeff Byers, who began training camp in contention for a starting job at right guard, was projected as Kalil's backup. But Byers has missed more than a week of practice because of back soreness. Byers said Thursday that he would have surgery today to remove a cyst and would begin rehabilitation in about 10 days.
"When you have adversity, you can let it get to you or it can make you stronger," said Byers, who redshirted last season because of a hip injury that required surgery.
Redshirt freshman Nick Howell was switched from tackle to center during training camp and he will back up Kalil against Nebraska. Howell is the son of former USC All-American offensive lineman Pat Howell.
"He's really surprised us that he's picked it up as quickly as he has," Carroll said of Nick Howell.
Sophomore safety Kevin Ellison did not practice again because of a sore left knee that was hyperextended in practice this week. But Ellison reiterated that he planned to start against Nebraska.
"I'm on schedule," Ellison said.
Carroll said freshman Antwine Perez would start if Ellison could not play or was slowed by the injury against the Cornhuskers.
Freshman Taylor Mays will start at free safety in place of injured Josh Pinkard.
Sophomore Cary Harris will start at cornerback in place of sophomore Kevin Thomas, who sprained his ankle in the opener against Arkansas. Junior Terrell Thomas will start at the other cornerback spot.
Junior Mozique McCurtis and freshman Shareece Wright are backups.
Junior running back Chauncey Washington will play against Nebraska, but Emmanuel Moody or C.J. Gable will start, Carroll said.... Thomas Williams will back up starter Rey Maualuga at middle linebacker. Redshirt freshman Luthur Brown would be up next with senior Oscar Lua (hamstring) available on an emergency basis, according to Carroll.