And it was behind a hot-shooting performance from reserve guard Calvin Newell, who had a game-high 18 points on 7-for-13 shooting, including 4-of-8 from behind the arc.
They trailed 40-38 at halftime after Cougars guard Marcus Capers hit a three-quarter court shot at the buzzer before half.
But the Sooners regrouped after intermission.
After WSU scored the first points of the second half, OU used an 8-2 run to recapture the lead at 46-44 with 17:17 remaining.
The Sooners trailed only once more from that point on--they were down 48-47 at the 14:06 mark.
From there, OU used a 12-3 spurt to open up a double-digit lead inside of eight minutes.
It rode that to the finish line.
The Sooners outshot Wazzou 45 percent to 42.3 percent but lost the rebounding battle for the first time this season, 30-28.
OU forced 22 turnovers and committed just 11 of its own, while recording five steals.
With the victory, the Sooners now await a matchup with Santa Clara Friday at 11 p.m. CT.