LINCOLN, Neb. (AP) — Nebraska quarterback Tanner Lee is in the concussion protocol, and coach Mike Riley said Monday that redshirt freshman Patrick O'Brien would prepare as if he will be the starter for Saturday's game at No. 13 Penn State.

A Minnesota player fell on Lee's head shortly before halftime Saturday, Riley said, and O'Brien played the entire second half of the 54-21 loss.

Lee won't be able to participate in football-related activity early this week. Riley said he wouldn't rule out Lee for the game because the junior has a lot of experience and it's possible he will be cleared. Riley said Andrew Bunch, a sophomore walk-on who played at Scottsdale (Arizona) Community College last year, would be the No. 2 quarterback if Lee can't play.

Regardless of who starts, the Cornhuskers (4-6, 3-4 Big Ten) face a difficult task after losing four of their last five games. The Nittany Lions (8-2, 5-2) have won 13 straight home games and are favored by 24 points.

O'Brien has appeared in three games, with his most extensive action coming against Minnesota. He was 12 of 18 for 137 yards and picked up 41 yards on five carries, but those rushing yards were wiped out by the six sacks he took. Three of those sacks came on the last four plays of the game.

"I was proud of Patrick, actually," Riley said. "It's a horrible time to have to play in a game where you're just passing almost all the time and they're teeing off with blitzes and rushes and so we get too much pressure. I thought he hung in there and made some beautiful throws and appeared to have a lot of poise. Everyone can see he has a big-time arm and can make some of those big throws and actually showed good mobility."

Nebraska drove to the Gophers 14 on its final possession, and Riley called three straight timeouts in the last 26 seconds, drawing boos.

"I hated to do that actually but ... here we are in a situation where we're in the red zone, he hasn't played much, who knows if he's going to play next week at that point," Riley said. "I was just going to give him more snaps. I know that' s not very popular, I know people don't like that."

O'Brien is a more capable and willing runner than Lee, but Riley said there probably won't be designed runs for him against Penn State. Riley said O'Brien's tendency is to decide to take off running quicker than Lee when the pocket begins to collapse.

Riley said there might be a smaller package of plays for O'Brien if Lee can't play.

"We're going to be playing a good defensive front," Riley said. "Less may be more."

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