FORT WORTH, Texas (AP) TCU had been close so many times in the closing 5 minutes of Big 12 games.
This time, the Horned Frogs didn't falter down the stretch.
Amric Fields had 12 points and a big part in an upset-sealing run as last-place TCU beat No. 21 Oklahoma State 70-55 on Saturday after the Cowboys had won three consecutive Big 12 games against ranked teams.
''Guys were locked in,'' Trey Zeigler said. ''To be able to close out a game like that was really good.''
Oklahoma State (17-8, 7-6 Big 12) was within 56-53 when Anthony Hickey found a wide-open gap and drove for a layup high off the glass with 4:52 left. But the Cowboys then went nearly 3 1/2 minutes without scoring as the Horned Frogs (15-10, 2-10) went on their second 10-0 run of the second half.
''It's pretty simple, but it's something we haven't been doing very well,'' third-year TCU coach Trent Johnson said. ''We made some shots, we got some key stops. ... We continue to grind.''
Fields started the final spurt with two free throws and later had an acrobatic driving layup to make it 64-53 with 1:38 left.
Kyan Anderson led TCU with 14 points despite 4-for-13 shooting, though the Frogs shot 52 percent overall (26 of 50). Zeigler added 13 points and Karviar Shepherd had 10, most of his coming in TCU's first 10-0 run.
Le'Bryan Nash had 19 points, but also committed seven turnovers for Oklahoma State. Jeff Newberry scored 10 points.
''I'm just disappointed. We just didn't respond very well. We were flat,'' Cowboys coach Travis Ford said. ''They outplayed us tonight, period. Plain and simple.''
Their first loss in nine trips to TCU came after the Cowboys had won three consecutive games against Top 25 teams for the first time ever in a regular season. They won at No. 16 Baylor on Monday night.
''We just came out sluggish,'' forward Michael Cobbins said. ''I don't know where it came from.''
Shepherd had the first two and then the last basket in the earlier 10-0 run for TCU in just over three minutes. His jumper with 16:43 left started that big spurt, and he had another after an Oklahoma State turnover.
Zeigler had two free throws with 15:52 left to give the Frogs their first lead of the second half at 38-37. Anderson then had a layup before Shepherd's dunk with 13:37 left made it 42-37.
The game was tied 10 times, the last when Nash made two free throws with 8:06 left to make it 48-all. Fields made two free throws 17 seconds later to put the Horned Frogs ahead to stay.
''We definitely thought we were going to get one,'' Zeigler said. ''We made an effort to say to everybody, `Let's fight, let's get back to fighting like we usually do.'''
There were six charging fouls called in the first half, three against each team. The first came in the opening minute of the game, when Phil Forte III drew a foul against Anderson. TCU forward Kenrich Williams was the only player who was called for a charging foul and also drew one - getting in front of Nash with 5:20 to go in the first half. Appropriately enough, the last charge came in the final minute of the half, called against Oklahoma State's Leyton Hammonds. There were no charges after halftime.
The Horned Frogs had a 2-0 lead even before the opening tip. Oklahoma State was assessed a technical foul for dunking during pregame warmups. That led to Anderson getting two free throws, and making them both. He was alone at the line, while the rest of the starters for both teams were near midcourt waiting for the tip. ''It's not a great way to start,'' Ford said. ''But you've got 40 minutes to make up for it.''
Oklahoma State: The Cowboys had won their first eight games against Texas teams this season. ... Oklahoma State was playing an unranked team for the first time in six games, with home games next week against No. 14 Iowa State and West Virginia, the team tied with them at No. 21 in this week's poll.
TCU: The Horned Frogs played their seventh ranked opponent in a span of eight games.
Oklahoma State: Home against No. 14 Iowa State on Wednesday night.
TCU: Home against Kansas State on Wednesday night.