Tennessee trailed the Bulldogs, 54-50, at halftime.
Tyreke Key, a transfer from Indiana State, scored 26 points to lead Tennessee. He was 8-for-12 from the field and converted four shots from beyond the 3-point arc.
Uros Plavsic finished with 13 points, making all six of his shots from the floor.
Tennessee freshman Julian Phillips scored 12 points in the second half. Phillips was called for two fouls in the first half.
PHOTOS: No. 11 Tennessee defeats No. 3 Gonzaga
Below are all Tennessee players who scored points against Gonzaga.