Middle Tennessee seemingly defended Old Dominion once they got off the bus.
Perrin Buford scored 17 points, Jaqawn Raymond added 13 points, and Reggie Upshaw contributed nine points and nine rebounds for the victorious Blue Raiders who will now face UTEP in the semifinals on Thursday.
Middle Tennessee was able keep ODU out of the paint and made scoring pretty difficult throughout, bursting the Monarchs on the bubble status with gritty, elite team defense.
It would take the Monarchs 8:20 to get on the board when Trey Freeman finally got a jumper to go down for their first score. Freeman would add another jumper a little more than 30 seconds later, then ODU went on an almost three minute scoring drought but were only down 12-6 after Javonte Douglas snapped the second drought at the 9:35 mark with a bucket.
Middle wasn't very sharp themselves by committing seven turnovers in the first half and shooting 40 percent in the half, Trey Freeman scored 15 of ODU's 20 first half points, as the Blue Raiders took a 25-20 lead at halftime.
Old Dominion opened the second half with a 16-4 run after Freeman and Aaron Bacote rained home back-to-back threes to polish off the run, putting ODU in front 36-29 at the 14:46 mark of the second half.
Middle would answer on the defensive end, holding ODU to only one field goal for almost another three minute stretch, while Jaqwan Raymond sank a set shot off a screen from three point land to tie things up at 38 as time ticked under the 10 minute mark.
Javonte Douglas would score six of ODU's next eight points, finishing the stretch with a fast break dunk to put ODU back in front 46-42 prompting a Kermit Davis timeout at the 5:37 mark of the second half.
Davis' timeout settled the Blue Raiders into a 9-0 run as Upshaw sent the game into the under four timeout with a layup to cap off the run, pushing Middle Tennessee ahead 51-46 with 3:01 left in the game.
The Monarchs would go 1/5 from the field in the final 3:01, while Buford sealed the win with three straight free throws in the final 30 seconds to notch the first upset in the tournament.
Middle Tennessee finished the game on a 17-6 run since they trailed Old Dominion 46-42 with just under six minutes left in the second half.
Despite the offensive struggles, ODU shot for a better percentage than Middle Tennessee, as they shot 42.6 percent from the field compared to MTSU's 38.1 percent.
The Monarchs left a lot of points on the floor thanks to their 8/19 shooting from the free throw line, including a couple of key misses in the final two minutes.
Trey Freeman poured in a game high 24 points for the Monarchs who will now wait for their NIT fate with their 24-8 record.
Tomorrow's UTEP versus Middle Tennessee semifinal starts at 2:30 p.m. Mountain Time, shown live on the CBS Sports Network