Watch: Monster putback dunk in OT helps Grambling State advance in NCAA Tournament

Grambling trailed by 14 at halftime but made a run in the second half. Ultimately, they took the lead with under six minutes to go following a monster 15-0 run. The Bobcats responded over the final minutes before a layup from the Tigers' Jimel Cofer with 37 seconds on the clock forced the extra session. 

Grambling outscored Montana State 16-9 in OT, pulling away in the waning moments thanks to Smith's dunk. 

Smith recorded 18 points and a team-high nine rebounds and was one of four Tigers to finish in double figures. Fellow starter forward Antwan Burnett also had 18 points, and backup guard Mikale Stevenson added 10 points. 

Meanwhile, Cofer was an unlikely standout on Wednesday, coming off the bench to ignite the Tigers' offense. Entering the matchup averaging 2.8 points on 42 percent shooting this season, the sophomore guard erupted for 19 points (7-of-9) off the bench, including several huge shots in the late going. 

Grambling started the year 2-10. Now, they head to Indianapolis to take on top-seed Purdue in the tournament's first round on Friday, March 22, at 7:25 p.m. 

While they might need a miracle to keep their incredible ride going, head coach Donte' Johnson said an upset begins and ends with stopping Boilermaker's star center Zach Edey. 

"Start on film and worry about how we can throw the whole house, the kitchen, whatever, the backyard at Zach Edey. We just have to figure it out," Johnson told CBS Sports. "We'll let the chips fall where they may. They didn't expect us to win this one."