On the next play, kicker Brock Warren missed a 20-yard field goal.
Keeton played the rest of the game, but Utah State started rushing the ball effectively enough that he didn't have to throw often in the red zone.
Since bursting onto the scene as a true freshman in 2011, Keeton has struggled with injuries.
The game against Nevada was his fifth this year and 14th over the past seasons. He had played only three snaps since spraining his knee at Washington on Sept 19.
Baffling Pack
One of the most inexplicable results in the Mountain West Conference this season involved Nevada.