Kalib Boone and Moussa Cisse each scored 18 points to lift Oklahoma State to a 71-61 victory over Oklahoma on Wednesday in Norman, Okla.
The Cowboys punished the Sooners inside from start to finish, with Boone and Cisse leading the way.
Oklahoma State (13-9, 4-5 Big 12) outscored Oklahoma (12-10, 2-7) 44-22 in the paint and 13-2 on second-chance points.
Boone made his first eight shots, not missing until nearly four minutes into the second half. He finished 8 of 10 from the floor.
Cisse had scored just one point and played just 23 combined minutes over the Cowboys' last four games as he continued to deal with the effects of an ankle injury suffered in early January.
He was scoreless in just two minutes in Oklahoma State's 72-56 win over the Sooners on Jan. 18.
But Cisse didn't look bothered by the injury on Wednesday, scoring a season-high 18 points on 8-of-10 shooting in 18 minutes.
The Cowboys have won four of their last five games, while the Sooners have lost four consecutive conference games and seven of their last 10 overall.
Oklahoma was coming off a 93-69 victory over then-No. 2 Alabama on Saturday at home.
But there was no such home-court magic for the Sooners on Wednesday.
The Cowboys got out in front quickly, as Oklahoma missed its first four field-goals attempts.
Boone scored eight consecutive points as Oklahoma State jumped up 10-2 before Oklahoma hit its first field goal more than four minutes into the game.
The Cowboys needed just over five minutes to stretch their lead to double figures, and the Sooners didn't get closer than seven the rest of the way. At its peak, the Oklahoma State lead reached 22.
Boone scored 12 of his points in the first half, as Oklahoma State led 42-28 at the break. Cisse scored 12 of his points in the second half.
Avery Anderson III added 12 points and Bryce Thompson finished with 11 in the victory.
Grant Sherfield led the Sooners with 14 points, going 4 of 12 from the floor. Milos Uzan added 11. Oklahoma was just 5 of 22 from beyond the arc.
--Field Level Media