The fifth-ranked Jayhawks wrapped up the outright championship before tipoff against Oklahoma State because Texas and Iowa State lost earlier. Marcus Smart made it bittersweet by scoring 20 of his 21 points in the second half to help the Cowboys defeat Kansas 72-65.
"To me, we missed our opportunity to celebrate," Jayhawks coach Bill Self said.
Andrew Wiggins scored 15 points, Joel Embiid had 13 points and 13 rebounds, and Wayne Selden added 13 points for Kansas (22-7, 13-3).
Oklahoma State (19-10, 7-9) overcame a 10-point deficit in the second half. The Cowboys shot 64 percent from the field after the break.
"What's frustrating to me is we had the game where we wanted it and then we didn't make competitive plays down the stretch to give us the best chance to win," Self said.
Kansas committed 22 turnovers, most of which Self thought were avoidable.
"I think it was more us tonight than them," he said. "They did a good job of jumping up in passing lanes and things like that, but there were more poor plays than there were good plays. They did a good job guarding us, don't get me wrong, but most of our turnovers, I think, were more self-inflicted than it was them pressuring us into them."
Markel Brown scored 21 points and Le'Bryan Nash added 16 points for Oklahoma State, which got away with being outrebounded 42-24.
Wiggins' three-point play tied the game at 64 with just over 2 minutes to play.
Kamari Murphy's layup gave Oklahoma State a 66-64 lead with 1:37 remaining. Kansas' Naadir Tharpe missed a jumper, and Murphy pulled in the rebound.
Smart made a layup with 46.1 seconds left to push Oklahoma State's lead to four, then he broke the press and hit another layup with 23.8 seconds to go to put the game out of reach.
The Jayhawks led 26-25 at halftime despite 35 percent shooting.
Oklahoma State shot just 24 percent in the first half but forced 11 turnovers. Nash and Brown scored nine points each to keep the Cowboys in the game. Smart had one point on 0-for-7 shooting.
Wiggins scored five points in the half but committed two fouls.
Brown hit a 3-pointer in the opening seconds of the second half to give Oklahoma State a 28-26 lead, but Kansas answered with a 3-pointer by Selden.
Smart made his first field goal, a 3-pointer, with 17:46 to play.
He drew the third foul on Embiid with 14:19 to go and the Jayhawks up 38-36. Wiggins picked up his third foul 11 seconds later.
Kansas responded with a run. With both freshman stars on the bench, Tharpe and Selden drained 3-pointers that put the Jayhawks up 46-38. A three-point play by Perry Ellis pushed Kansas' lead to nine, and a pair of free throws by Wiggins extended the margin to 10 for the first time.
Oklahoma State muscled its way back into the game with a three-point play by Nash and a long lob by Smart to Brown that cut Kansas' lead to five and got the crowd back into the game. The Cowboys moved into the double bonus with 5:50 remaining, and Brown made two free throws to give Oklahoma State a 60-59 lead.
Nash picked up his fourth foul with 4:35 remaining, but Smart calmed him down after Nash disagreed with the call.
Wiggins picked up his fourth foul with 4:09 to play, and Smart's 3-pointer with 3:44 left put Oklahoma State up 63-61.
From there, Kansas couldn't come back.
"We just weren't aggressive," Selden said. "We weren't getting stops. That was the biggest thing."
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