Manziel was injured when he was tackled on an 8-yard run early in the fourth quarter. It was unclear what his injury was.
He got up after the tackle and then went to the ground before he reached the A&M sideline. A&M officials looked at him for a couple of minutes on the turf before he got up and walked off on his own power.
He was replaced by Matt Joeckel with A&M leading 31-24. The Aggies made a field goal two plays after he left to make it 34-24.
He came back in the game with nine minutes left and Auburn leading 38-34.