Working with just six scholarship players, the USC offensive line got even thinner when junior college transfer Jeremy Galten left practice with a left knee injury.
Coach Lane Kiffin said Galten, who had been playing mostly at right tackle, would undergo X-rays.
"That would hurt us, our ability to practice, losing another offensive lineman," Kiffin said.
Galten signed with USC and enrolled in January from San Mateo Junior College, along with David Garness, to serve as a stopgap this spring and hopefully provide depth.
The Trojans are already missing two projected starters, as Kevin Graf is recovering from shoulder surgery and Khaled Holmes is limited by neck stingers. Backup Abe Markowitz is back in a walking boot after missing all of last season with a broken foot.
Early hour notwithstanding, New York Jets quarterback Mark Sanchez returned to the USC campus Thursday to meet with coaches and players and attend practice.
"I don't know if I was here that early when I was in school, but it was fun," he said.
"I like to get a little lunch, maybe a nap and then get to practice. But these guys did a great job with it and just mixing things up."
Sanchez, who led the Trojans to a 12-1 record and Rose Bowl win in 2008, was scheduled to participate in an on-campus roundtable about the state of the NFL on Thursday evening. He has been working out in Los Angeles waiting for a resolution to the current lockout.
In a team meeting before practice, Sanchez stressed the importance of completing a degree before trying to play professionally.
He also worked with the quarterbacks, even breaking out hand signals used by his offensive coordinator Steve Sarkisian to relay plays in from the sideline.
"It was good to hear from a guy who is in the league, hear his perspective on things and pointers, what he is thinking and doing right now," quarterback Matt Barkley said.
Detroit Lions defensive end Lawrence Jackson also attended practice.
Running back Marc Tyler returned to action after pulling his hamstring on the first day of spring.
"I wanted to get back out here," he said. "It was boring. I'd rather be out here than be over there running."
Tyler was originally supposed to be limited to only individual drills and 7-on-7, but felt well enough that trainers let him complete practice.
Without a bowl game, Tyler ballooned to 230 pounds in the offseason. He plans to play his senior season at 217 pounds, the same as he weighed last year when he led the team with 913 rushing yards and nine touchdowns.
-Wide receiver Markeith Ambles did not practice Thursday after missing a weightlifting session earlier this week.
-Cornerback Tony Burnett was in Texas with the USC track team Thursday for a meet. He is also likely to miss practice Saturday.
-Kiffin praised safety Demetrius Wright and indicated the sophomore would be a viable candidate to start opposite T.J. McDonald.
"Demetrius has really flashed, shown speed, shown the ability to hit, the ability to tackle," Kiffin said. "As we get through this spring and get to the fall, I think he'll really push all those guys."
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