Former St. Bonaventure High linebacker Rey Maualuga is one of four USC football players not in uniform today at the Coliseum.
The Butkus Award candidate injured a knee in last week's loss to Oregon State.
Other Trojans out of action include bruising tailback Allen Bradford (hip), right guard Zach Heberer and tight end Rhett Ellison.
Right guard Alex Parsons, tight end Anthony McCoy, tailback C.J. Gable and nose tackle Christian Tupou are among the USC starters.
Maualuga's injury and the demotion of nose tackle Averell Spicer and defensive end Everson Griffen means that Matthews is at defensive end, Michael Morgan starts at strongside linebacker and Brian Cushing moves to middle linebacker.