Notre Dame quarterback Jack Coan limped off the field after a sack and went into the medical tent during the third quarter of Saturday's Top 25 matchup against Wisconsin.
Coan attempted to throw on the sideline after coming out of the tent but could not complete his normal follow through without showing considerable pain.
Coan, who threw for 158 yards on 15-of-29 passing and a touchdown, left the field for the locker room. He came back to the field with his helmet on but did not re-enter the game.
The Fighting Irish's (3-0) hopes of remaining undefeated on the season lie in the hands of redshirt freshman quarterback Drew Pyne, who replaced Coan on the field.