Nebraska has been hampered by injuries this season. Starting running back Tre Bryant and center Michael Decker are already out for the season, and now linebacker Luke Gifford will also miss the reminder of the year due to hip surgery, Mike Riley said on Monday.

Gifford, who’s been a leader for Nebraska’s defense when healthy, has 39 tackles in seven games but missed the last three games with the injury.

Quarterback Tanner Lee is also in danger of missing Nebraska’s game against Penn State on Saturday. Lee missed the second half against Minnesota last Saturday, after suffering a concussion.

He’s currently in the concussion protocol, but the signs point to Patrick O’Brien making his first career start at Penn State on Saturday.

O’Brien came in for Lee against Minnesota after halftime, going 12-of-18 passing for 137 yards. He also rushed five times for 41 yards but was sacked six times, causing him to finish with zero net rushing yard.

“I don’t rule him in or out right now. He’s in that (concussion) protocol, and you know how that goes,” said Riley at his Monday press conference. “It’s a day-to-day thing where only the medical people can come back and say if and where he’s cleared to play.”