However, the injury is not considered serious and he is expected to resume workouts on Tuesday, when the team returns from its Christmas break. There will be no practices on Sunday or Monday.
USC center Jeremy Hogue has been awarded a $5,000 NCAA postgraduate scholarship.
He has received nearly $40,000 in scholarships from the National Football Foundation, the NCAA and USC. Hogue, who had a 3.9 grade-point average as an undergraduate, earned his bachelor's degree in political science and is studying for a master's.
After watching Northwestern on film, USC Coach John Robinson says the Wildcats "look like the third-best team in the nation."
"They play games very well," Robinson said. "They don't screw up much. They are physical and talented, and anybody who says they are overachievers isn't paying attention."
Robinson describes the Trojans' attitude as great.
"Everybody felt wounded after the UCLA game, but we're fine now," he said. "Our underlying concern is the inconsistency that we showed late in the season after being so consistent earlier."