Steven Santa Ana's layup tied the game for Elon at 60 with 1:57 to play. Each team missed two shots down the stretch before Pusica's shot was off at the buzzer.
Brace opened the extra period with consecutive 3-pointers and added two free throws. Pusica scored the last four points on a jumper and a pair of free throws.
Northeastern held Elon's leading scorer Tyler Seibring (16.9 points per game) to 1-of-17 shooting and three points.
The Huskies improve to 2-0 against the Phoenix on the season. Northeastern defeated Elon 81-70 on Jan. 10. Northeastern (15-9, 9-3) plays UNC Wilmington on the road on Thursday. Elon matches up against William & Mary at home next Saturday.