KANSAS CITY, Mo. -- It was a game that lived up to the hype, then exceeded it.

Buddy Hield scored 39 points, including 21 in the second half, as the sixth-ranked Sooners held on to defeat 21st-ranked Iowa State 79-76 Thursday in the quarterfinals of the Big 12 Conference tournament at Sprint Center.

As good as Hield was, Iowa State forward George Niang was almost as good. Niang scored 25 of his 31 points after intermission before fouling out with 31 seconds left.

"Buddy was amazing, but George's second-half effort was just as good," Iowa State coach Steve Prohm said. "He kind of willed us back into the game. We just couldn't make enough plays down the stretch to finish or to push it into overtime or whatever."

Hield and Niang have developed a friendship after facing each other for the past four years. Hield was able to laugh about it after the game.

"It was fun competing against him," Hield said. "He is a good competitor, a tough matchup to guard. He uses his body so well, so skilled. Going against guys like Niang is fun. Thank God we got the win. It's sad to see him lose, but I am sure he will challenge me the next game."

Meanwhile, Niang had remorse that he hadn't done more.

"From a friendship standpoint, I am happy to say that he is my friend and I am proud of him," Niang said. "But from a competitor standpoint, I wish he'd miss a couple more shots.

"I wanted to get in and try to pierce through the defense to get them to over-help so I could start finding shooters and making plays. They gave me lanes to the rim, so I just was going to the rim and was able to finish."

The Sooners (25-6) play ninth-ranked and second-seeded West Virginia in the second semifinal Friday.

Forward Ryan Spangler and guard Isaiah Cousins each had 10 points for Oklahoma, and Spangler pulled down a game-high 12 rebounds.

Forward Matt Thomas had 13 points for Iowa State, while forward Deonte Burton had 12 and Abdel Nader added 11.

But this game was all about Hield and Niang.

Hield took over the second half, much as he did in the first. He scored 15 of his team's first 24 after the break. His driving layup helped give Oklahoma a 59-45 lead with 9:45 left.

Iowa State responded with a quick seven-point spurt to cut the lead in half. Niang scored 14 straight Iowa State points, and his driving layup with four minutes remaining cut the lead to 67-61.

Spangler answered with a three-point play, coming on Niang's fourth foul, with 3:36 left.

The Cyclones cut it to 72-66 and got a turnover but couldn't convert it into points. Spangler rebounded guard Monte Morris' miss and made one of two free throws to extend the margin to 73-66 with 1:25 left.

Nader hit a 3-pointer to cut the Cyclones' deficit to 73-69. After a shot-clock violation on Oklahoma, Nader missed an open 3-pointer that would have cut the lead to one point. Spangler got the rebound and made both free throws with 38.3 seconds remaining.

"Niang is such a good player," Oklahoma coach Lon Kruger said. "I told him afterwards it's really an honor to have coached and participated against him for four years. He is so respectful, and he and Buddy respect each other so much because they always lay it out there.

"It was fun. It was two really, really good players going nose to nose oftentimes, and George got his share of wins out of it, for sure."

Niang scored to slice the lead to 75-71, but he fouled out on the inbounds play. Hield hit both free throws, and the victory was all but secured. Burton's long-range 3-pointer at the buzzer accounted for the final margin.

Neither team grabbing a lead of more than three points until less than three minutes remained in the first half. Hield's two free throws gave Oklahoma a 30-26 edge. The lead was extended to six points before a 3-pointer by Thomas cut it to three. Jordan Woodard answered with a 3-pointer of his own to give the Sooners a 35-29 halftime lead.

NOTES: Iowa State won the last two Big 12 tournament titles, defeating Kansas in 2015 and Baylor in 2014. The Cyclones were trying to win three straight. The only teams to claim three straight are Kansas (twice) and Oklahoma. ... Oklahoma was the tourney champ from 2001-03. ... This was the 200th meeting between the Cyclones and Sooners. Oklahoma leads 115-85, including 14-13 in neutral-site games (13-12 in Kansas City).