Gonzaga, the No. 1 seed, used a game-closing 8-2 run to defeat No. 16 Southern 64-58 in a first-round NCAA men's tournament game in Salt Lake City, Utah.
Derick Beltran led Southern (23-10) with 21 points.
Kelly Olynyk scored 21 points and had 10 rebounds for Gonzaga (32-2).
Beltran hit a jump shot to tie the score at 56 with 3:46 remaining in the game.
But Gary Bell Jr. came back with a 3-pointer to give Gonzaga a 59-56 lead with 3:19 left. Beltran hit a free throw to cut the score to 59-57 with 2:28 remaining.
Gonzaga's Kevin Pangos hit a 3-pointer to make the score 62-58 with 1:55 left.
Southern led three times in the first half, but trailed 34-31 at halftime.