Stefanini scores 20 to lead Columbia over Penn 79-77 in OT
Ellis sneaked under the Columbia basket to take the inbounds pass and score with 0.4 seconds left.
Ellis's basket capped a comeback from a 77-72 deficit with 1:23 remaining.
Stefanini scored in the paint to tie the game at 72-all with 33.2 seconds left in regulation and send it into overtime.
Ellis had 14 points for Columbia (7-16, 2-7 Ivy League), which ended its six-game losing streak. Patrick Tape added 14 points, nine rebounds and three blocks. Quinton Adlesh had six rebounds for the visitors.
Antonio Woods had 16 points and eight rebounds for the Quakers (15-10, 3-6). Jake Silpe added 14 points and six rebounds. AJ Brodeur had 13 points and seven assists.
The Lions leveled the season series against the Quakers with the win. Penn defeated Columbia 72-70 on Feb. 2. Columbia faces Princeton on the road on Saturday. Penn faces Cornell at home on Saturday.