USC linebacker Morgan Breslin has been sidelined several games because of injury, and the senior apparently won't be returning to the lineup any time soon.
"We don't know exactly, right now, how long he's going to be out, but it looks like it's going to be an extensive period of time," interim Coach Ed Orgeron said Tuesday during the weekly Pac-12 teleconference.
USC plays California on Saturday at Memorial Stadium in Berkeley.
Last season, the 6-foot-2, 250-pound Breslin had a team-best 19½ tackles for losses, including 13 sacks.
He sat out this season's opener against Hawaii because of a foot injury suffered during training camp but played in the next four games. He started but was sidelined against Arizona because of what Orgeron said was a hip injury, and then returned against Notre Dame. But he has sat out the last two games.
Breslin has eight tackles for losses, including 4½ sacks, which rank third on the team. Linebacker Devon Kennard has seven sacks, end Leonard Williams five.
Orgeron and the Trojans miss Breslin's presence in the lineup.
"In my 27 years of coaching, Morgan Breslin is absolutely one of my favorite players I've ever coached," Orgeron said.