STILLWATER, Okla. -- Marcus Smart and Le'Bryan Nash combined for 54 points and made critical plays late, lifting Oklahoma State past Oklahoma, 84-79, in a Big 12 Conference overtime thriller at Gallagher-Iba Arena.
Smart scored a career-high 28 points and Nash added 26, including seven in the extra period, as the No. 17-ranked Cowboys ran their winning streak to seven games and remained in a tie for first place.
Oklahoma State improved to 19-5 overall, 9-3 in the conference. The Sooners dropped to 16-8 and 7-5.
Both teams had opportunities late in regulation, with Oklahoma's Romero Osby missed a hurried running shot as the shot clock neared zero.
Following a timeout, Smart got an open look at a 3-pointer, but his shot at the buzzer clanged off the rim.
Both teams owned big leads, with the Cowboys jumping out to a 19-8 margin to start the game. The Sooners led, 45-34, early in the second half.
But Oklahoma State used a spurt to pull close and the two teams jockeyed for the lead the rest of the way.
Ultimately, the game flipped in the Cowboys' favor in the final minute of overtime on two defensive plays.
First, Markel Brown worked a steal of the Sooners' Sam Grooms, leading to Michael Cobbins' layup that bumped the Cowboys' lead to 82-79.
On Oklahoma's next possession, Smart tied up Steven Pledger, with the possession arrow pointing Oklahoma State's way. Smart's two free throws sealed the verdict.
Grooms scored a career-high 18 for Oklahoma, which also got 18 points each from Pledger and Romero Osby.
The Cowboys seemed to grab control at the outset, jumping out to a 19-8 lead by the 11:49 mark. Three players hit 3-pointers during that spurt and Oklahoma State had the rhythm and pace in their favor.
But Oklahoma tightened its defense, turning the momentum, leading to a 27-8 surge that produced a 35-27 lead at halftime.
The Sooners, after a sluggish start, heated up from the floor, with backup guard Grooms scoring six points during a three-minute flurry, four of which came as Oklahoma scored the final nine points of the half.
Grooms, who averaged 2.5 points a game coming in, led Oklahoma in the first half with nine points on 4-of-5 shooting.
Oklahoma State, after its strong start, finished at only 31 percent shooting (9-of-29) in the first half.
NOTES: The Sooners played without injured starter Buddy Hield, who suffered a broken foot in Monday night's victory over TCU. Hield was on the bench, with crutches. He's projected to miss the rest of the regular season, but could be available for postseason play. ... While Gallagher-Iba Arena has proven to be one of the tougher places to play in the Big 12, if not the country, Oklahoma has enjoyed decent success there, winning three of their last five in the arena. ... Oklahoma State remains in the Big 12 race in mid-February for the first time since 2005.