NORMAN, Okla.-- Buddy Hield scored 22 and Ryan Spangler had 16 points and 15 rebounds as Oklahoma knocked off previously undefeated Iowa State, 87-82, at Lloyd Noble Center on Saturday.
Isaiah Cousins came off the bench to score 17 points as the Sooners (13-3) twice let big leads slip away before finally finishing off the upset.
DeAndre Kane had 23 points to lead No. 9 Iowa State, while Melvin Ejim added 21.
The Cyclones (14-1) came back from 13 points down to take the lead with 2:39 remaining on Ejim's 3-pointer, only Iowa State's second basket from behind the arc in the second half.
But Spangler, as he did all day, made a big play inside for the Sooners. He spun in the lane, hit a contested shot and drew a foul to put Oklahoma back up by three.
Seven of Spangler's rebounds came on the offensive end.
The Sooners then denied Iowa State a shot until Ejim's wild 3-pointer at the shot-clock buzzer missed everything and Oklahoma finished it off at the free-throw line.
Oklahoma started the second half in a big way, outscoring the Cyclones, 20-7, in the first six minutes-plus.
The Sooners had been struggling from behind the 3-point line in the second half since Big 12 play began, but came out hot against Iowa State.
Oklahoma hit five 3-pointers in that stretch.
But as it did in the first half, Iowa State charged back.
Oklahoma led for much of the first half, building an eight-point lead late in the half on Buddy Hield's alley-oop feed to Cameron Clark.
Clark, the Big 12's leading scorer, couldn't find much room early, drawing constant double teams from the Cyclones.
But Clark broke out during a three-minute stretch to help Oklahoma stretch the lead to eight. The run began after Clark beat Naz Long to a loose ball near midcourt and went straight to the basket.
Clark drove on Matt Thomas, hitting a layup and drawing a foul.
The Sooners again led by eight with a little more than two minutes remaining before the Cyclones closed the half with eight consecutive points to tie the game for the first time since the opening minute.
Georges Nang scored six of his 12 first-half points in the stretch.
The Sooners built the lead with the help of a strong inside performance from Spangler.
Spangler, who was limited by foul trouble in Oklahoma's loss to Kansas on Wednesday, kept Nang in check early and came up with several rebounds in the opening minutes.NOTES: DeAndre Kane of Iowa State was helped off the court in the final minute after apparently sustaining an ankle injury. ... Oklahoma has 21 3-pointers in the first half in its first three Big 12 games. ... For the first time since injuring his calf on Dec. 14 against Tulsa, Spangler did not wear a wrap on his right leg. ...... Iowa State's 14-game winning streak was the longest in school history. ... The Cyclones were only 3-of-13 on 3-pointers in the first half and 6-of-26 in the game.