Thompson got the start over Travis Wilson and led the Utes to a touchdown on their first drive. On Utah's next drive, Thompson's knee appeared to buckle as he threw a deep pass. The junior went down and needed to be helped off.
He left the sideline and returned later in street clothes.
Thompson ran for 28 yards and was 4 for 5 for 23 yards.
Wilson has started seven games this season, though Thompson has played often. Coach Kyle Whittingham reopened the competition for the starting job this week after Wilson struggled against Arizona State.