Petty was concussed in the third quarter of Saturday's win over Texas Tech. He left the game and did not return.
Baylor, ranked sixth in this week's College Football Playoff rankings, must win against the ninth-ranked Wildcats to remain in consideration for one of the four playoff spots.
Petty has thrown for 2,893 yards with 25 touchdowns and five interceptions this season. Under his direction, the Bears lead the nation in yards and points per game.
- Dan Gartland