LOS ANGELES -- USC coach Lane Kiffin said he is "extremely hopeful" that quarterback Matt Barkley will be able to play Saturday against rival Notre Dame.
Barkley injured his left ankle in the first half of the Trojans' 36-7 loss at Oregon State Saturday. X-rays on the quarterback's sprained ankle showed no broken bones.
The history of Barkley's injury, a high ankle sprain, would suggest his return this weekend is doubtful. He spent the second half on crutches with his left foot in a walking boot. He was injured when an Oregon State defensive lineman rolled over his leg.
If Barkley can't go, Kiffin said fifth-year senior Mitch Mustain, a transfer from Arkansas, would make his first USC start.
"Unless you want us to start [walk-on] John Manoogian, we'll be going with Mitch," Kiffin told reporters Sunday night. "We have great confidence in Mitch. He's played well in scrimmages since he's been here. We look for him to play a lot better Saturday."
Mustain completed eight of his 17 passes for 60 yards and was sacked twice Saturday. Barkley, a sophomore, is the No. 4-rated passer in the Pac-10 with 25 touchdown passes and 10 interceptions. The USC offense is coming off its worst performance of the year. It had 10 drives that lasted five plays or fewer against the Beavers.
Middle linebacker Chris Galippo had to leave Saturday's game with a concussion. Kiffin said Galippo will be held out from practice early in the week.
Mark Saxon covers USC for ESPNLosAngeles.com. Information from The Associated Press contributed to this report.