Top-seeded Oklahoma State hosts unseeded Eastern Washington in the second round of the NIT on Sunday afternoon in Stillwater, Okla.
The Cowboys (19-15) are coming off a 69-64 victory over Youngstown State on Wednesday.
Eastern Washington (23-10) earned just its second postseason win as a Division I program with an 81-74 road win over fourth-seeded Washington State on Tuesday.
Oklahoma State, which had to play at Youngstown State because of a venue conflict at its homecourt of Gallagher-Iba Arena, overcame a slow start against the Penguins.
Trailing 49-41 with 14:54 left, the Cowboys responded with a 15-5 run to take a lead they wouldn't relinquish on John-Michael Wright's layup with 5:46 remaining.
Tyreek Smith (13 points, 12 rebounds), Moussa Cisse (10 points, 13 rebounds) and Quion Williams (11 points, career-high 11 rebounds) each had double-doubles, marking the first time three Cowboys accomplished the feat in the same game since 2009.
Bryce Thompson finished with 11 points and four rebounds for the Cowboys, who have won three of their past four games.
"I think everybody's motivated because we felt like we should've made the tournament -- March Madness," Smith said. "We just feel like we could win this whole (NIT) to show them that we deserved to be there."
Eastern Washington also rallied to keep its season alive.
Trailing 60-51 with 11:31 left, the Eagles tied the game at 74 on Angelo Allegri's layup with 1:09 left. Steele Venters' 3-pointer gave Eastern Washington the lead for good with 16 seconds remaining.
Venters, the Big Sky Conference Player of the Year, secured the win by making two free throws with three seconds to go, ending the Eagles' three-game losing streak.
"Our guys didn't try to force it inside but did it through the rhythm of the game," Eastern Washington coach David Riley said. "It's a game of runs. We knew playing WSU ... that is something they do. We just had to get back to our identity on defense (to stop it)."
Venters, who averages a team-high 15.7 points per game, finished with 27 points. Tyreese Davis and Allegri each added 12 points and five rebounds.
The Eagles' first victory in the NIT in school history marked their first postseason win since a 79-72 triumph over Pepperdine in the CBI in 2016.
--Field Level Media