OSU jumped out to a lead and held on for most of the game but the Jayhawks rallied and pushed the Cowboys to the edge.
This time OSU didn't fall.
Byron Eaton scored a career-high 26 points, including the game-winning free throw with 12.6 seconds left, and OSU knocked No. 4 Kansas out of first place in the Big 12 with a 61-60 upset on Saturday.
Eaton was fouled by Sasha Kaun as he drove to the basket and he made the first free throw before missing the second.
Kansas grabbed the rebound and worked the ball to Brandon Rush, but he missed a 3-pointer from the left corner before fans rushed the court to celebrate the Cowboys' third straight victory.
The Jayhawks (24-3, 9-3) rallied from a nine-point second-half deficit to go ahead 58-54 in the final 3 minutes. But Oklahoma State (14-12, 5-7) finished strong knocking Kansas out of a first-place tie with No. 7 Texas. The Longhorns beat Oklahoma 62-45 on Saturday.
Marcus Dove hit a 3-pointer to put the Cowboys ahead 60-58 with 58 seconds left, and Oklahoma City native Darnell Jackson made a spinning layup from the left block with 41 seconds remaining to tie it at 60.
Eaton then slowed the pace before charging into the lane and drawing a whistle under the basket. He went 16-for-18 from the free throw for the game and set a career-best in scoring for the second time in a three-game span.
After a slow start, Rush scored 10 points during a 19-6 run that gave the Jayhawks the late lead.
Rush converted a three-point play off an offensive rebound and then followed it with a game-tying 3-pointer from the left corner before Kaun's left-handed layup gave Kansas a 56-54 lead with 4:22 remaining. After two offensive rebounds by Kansas, Rush added a 17-footer for the four-point Kansas lead.
Jackson led Kansas with 16 points and 10 rebounds while playing three days after his 19-year-old cousin, Kascey Corie McClellan, died after getting shot earlier this month at an Oklahoma City nightclub. Backup guard Rodrick Stewart also played three days after Allen Stewart, his cousin and adopted brother, was shot and killed in Seattle.
Rush added 12 points, all in the second half, and Mario Chalmers scored 11. Darrell Arthur, Kansas' leading scorer, matched his season low with six points before fouling out with 6:04 remaining.
Kansas committed 21 turnovers, one below their season-high.
Obi Muonelo had 12 points for Oklahoma State, which has won four of five after its worst start in Big 12 history.
The Jayhawks came out shaky, turning the ball over on six of their first 10 possessions and missing badly on three of their first four shots. Jackson airballed a jumper from the right baseline and Chalmers barely scraped the rim with a 3-pointer from the left wing.
And the turnovers kept coming. Kansas couldn't get a shot off against Oklahoma State's zone before the 35-second clock expired, Russell Robinson threw an alley-oop pass for Rush that sailed into the crowd, and by halftime the Jayhawks had 14 turnovers and were down 36-32, the largest halftime deficit this season for the Jayhawks.
The Associated Press contributed to this story.