No. 13-ranked USC has one notable injury concern heading into its home opener Saturday night vs. Utah State, as coach Lincoln Riley designated starting linebacker Mason Cobb as questionable with an unspecified injury.

Cobb played the whole game in USC's 27-20 win over LSU last week, finishing second on the team with 7 tackles along with a game-sealing interception.

"Mason's been limited for us this week, hasn't been a full participant at practice, will be questionable for the game," Riley said Thursday. "We'll just kind of see how he moves around today, and obviously we've got a little bit of extra time for recovery now with the later kick. We'll see. It'll be close.

"If he's not able to go, we still have Eric [Gentry] and Easton [Mascarenas-Arnold] obviously, that next group of guys -- Desmon Stephens, Raesjon [Davis], [Elijah] Newby, [Garrison] Madden, that group. It would be a combination of all of those guys if Mason is not able to go. Hopefully he can, but if he can't it'll be exciting to see some of those guys get an opportunity."

The Trojans used Gentry in a variety of roles last week, including having him come off the edge a good bit. If Cobb is out, he could move back into a more traditional inside linebacker role next to Mascarenas-Arnold.

Stephens, a true freshman, would seem to be the next guy up otherwise.

"We've been impressed, really from spring on. He's kind of felt like he's belonged the entire time. He hasn't looked like a true freshman in terms of the way he competes," Riley said. "He's learned our defense fast, and we've got a lot of confidence in him. He'll have opportunities that are going to pop up more that he's going to create by continuing to improve as this year goes on, but yeah, he's certainly a guy you look at and can envision him -- he's going to have a bright future here. I think if he stays on track and stays hungry and keeps improving, we can all see that.

"But he's certainly going to have an ability to impact this team right now, so I'm looking forward to hopefully getting some of these opportunities to play in some games and get to really show it because there is a real talent there that you're pretty excited about because he's a pretty mature competitor for his age and he's physically pretty mature. He has the tools capable of making an impact early on."