San Antonio led 72-69 with 46 seconds left on Lewis' layup, but on the next possession Aaseem Dixon nailed a 3-pointer to tie it. Quinton Upshur's 3-point attempt at the buzzer for Northern Arizona missed and it went to overtime.
The game was tied at 11 early on, but Northern Arizona went on a 13-2 run - highlighted by a pair of 3-pointers by Dixon - and led 44-35 at the break. UTSA scored the first 10 points of the second half to get back into the game.
Dixon finished with career-highs in points (31), 3-pointers made (9) and attempts (19). Upshur had 17 points but was 1 of 11 on 3-pointers.