Canada's Andrew Wiggins scored 30 points, Wayne Selden Jr. had 14 and No. 10 Kansas pulled away in the final seconds of overtime for a 77-70 victory over Oklahoma State in the quarterfinals of the Big 12 tournament.

Naadir Tharpe made four foul shots in the extra session to seal the victory for the top-seeded Jayhawks (24-8), who will face fourth-seeded Iowa State in Friday night's semifinals.

The No. 16 Cyclones, behind a big game from Melvin Ejim, beat No. 5 seed Kansas State 91-85.

Phil Forte briefly gave the Cowboys a 70-68 lead with a 3-pointer a minute into overtime, but the Jayhawks scored the final seven points, all but two of them coming at the foul line.

Le'Bryan Nash scored 19 points to lead the Cowboys (21-12). Forte added 16 points and Marcus Smart finished with 14, though he missed all three of his shots in the extra session.

Both teams had chances to earn the win in regulation.

Wiggins, from Vaughan, Ont., hit a baseline jumper with a minute left to knot it 67, but Cowboys coach Travis Ford decided against going 2-for-1 on possessions, and Smart missed a 3 with 32 seconds left.

The Jayhawks got the rebound and called timeout with 16 seconds left to set up a play for Wiggins, and he missed a tightly guarded 3 with a few ticks left on the lock. Tarik Black gathered in the rebound and stuck it back, but the basket came after time had expired.

Black got extended minutes in place of Joel Embiid, the Jayhawks' 7-foot freshman centre, who has been ruled out indefinitely with a stress fracture in his back. The senior transfer finished with seven points and 12 rebounds, including a couple with the game in the balance.

The Cowboys, who had to play a matinee after dispatching Texas Tech on Wednesday night, didn't look as if they were weary in the first half. They actually pulled out to an early lead, silencing a heavily pro-Kansas crowd that had packed inside the Sprint Center.

Kansas responded by taking a 32-23 lead into halftime, and then maintained its advantage early in the second half. But once Black and fellow forward Perry Ellis picked up their fourth fouls, the Cowboys started shredding the Kansas defence by driving the lane.

Smart proved to be the most adept at it, picking up fouls when he wasn't hammered on the way to the rim. But just about everyone wearing black and orange got into the act, and Oklahoma State methodically trimmed the lead to 55-49 with about 8 minutes to go.

That's when Cowboys coach Travis Ford changed things up by slapping on a full-court press. It produced two quick turnovers and helped Oklahoma State take a 60-59 lead with 4 minutes left.

It was the Cowboys' first lead since the 12-minute mark in the first half.

The two teams, who each won on their home floor during the regular season, traded blows down the stretch. Selden made a couple free throws for Kansas, Forte answered with two from the foul line for Oklahoma State. Black and Wiggins threw down alley-oop dunks for the Jayhawks, and Murphy hit a pair of free throws and Markel Brown hit a rainbow 3 to give the Cowboys the lead.

It just made sense that such a nip-and-tuck game would be decided in overtime.