Oklahoma State starting quarterback Wes Lunt was helped off the field with a left knee injury early in the first quarter of Saturday's game against Louisiana-Lafayette.
Lunt was hit by cornerback Melvin White as he scrambled backward and threw an incomplete pass on the Cowboys' first offensive series. He remained face down on the turf for a few moments and team doctors examined his knee before helping him limp to the sidelines.
Later in the first quarter, he headed to the locker room on crutches with a wrap around his knee.
Lunt, a freshman, was making his third start for Oklahoma State after taking over for first-round NFL draft pick Brandon Weeden. He set a Big 12 freshman record with 436 passing yards last week in a loss at Arizona.
Redshirt freshman J.W. Walsh replaced him.