Trailing by 10 at the break, North Dakota State (14-7, 6-2 Summit League) forced overtime when Dexter Werner went 1 of 2 from the line to tie the game at 47 with 56 seconds left. Both teams missed shots in the final seconds.
Paul Miller hit the go-ahead 3-pointer to make it 52-49 with 3:53 left in OT, then Alexander and Kory Brown both went 2 of 2 at the free throw line to extend the lead as the Bison held Denver (9-12, 3-5) scoreless for over three minutes in the extra period.
Brown finished with 11 points and 13 rebounds and Werner had 10 points.
Nate Engesser led Denver with 15 points and Brett Olson added 11.