OKLAHOMA CITY — LaceDarius Dunn hit six 3-pointers and scored 24 points, leading a late surge as Baylor rallied after blowing a 17-point lead to stun No. 11 Kansas 71-64 in the Big 12 tournament quarterfinals today.

The three-time defending champion Jayhawks (25-7) dispatched of the deficit quickly and led by five before Dunn fueled a decisive 12-0 run for the Bears (19-13).

Kansas became only the second top-seeded team to lose its opening game at the Big 12 tournament. Baylor was also responsible for the other upset, beating Iowa State in 2001.

Sherron Collins scored 14 of his 16 points in the second half to lead the Jayhawks, but he airballed a potential tying 3-pointer with 26 seconds left. Marcus Morris and Tyshawn Taylor added 12 points apiece for Kansas.

Kevin Rogers added 14 points and Curtis Jerrells scored 10 for the Bears, who advance to face either Kansas State or Texas in the semifinals on Friday.

The Jayhawks — the defending national champions — are solidly in the NCAA tournament, so the only thing in jeopardy is whether they'll get to play at a close-to-home Kansas City, Mo., in the first round. That could have been taken away at the hands of Dunn, who got Baylor off to a hot start and then finished strong.

He had two 3-pointers and a steal for a fast-break layup in the Bears' go-ahead spurt, and his 3 from the right wing gave the Bears a 65-58 edge with 3:41 remaining.

Tyrel Reed and Collins responded with back-to-back 3-pointers to pull the Jayhawks back within one, but Mamadou Diene protected the lead by swatting away Collins' potential go-ahead shot in the lane with 1:57 left. Rogers hit a pair of free throws at the other end before Collins missed on another drive to the basket before missing everything with his final 3-point attempt.

Collins also missed his first four 3-pointers and got off to a 1-for-8 start as Baylor built its big early lead. He made four straight shots to start the second half, but was 2-for-16 the rest of the game.

The Bears came out sizzling, knocking down five of their first 10 3-pointers and going 6-for-8 inside the arc to open a 30-13 lead on Jerrells' 3 from the left wing.

Aldrich then led the way as Kansas took over the boards and started to eat away at the deficit. He had a putback off of one offensive rebound and turned another into a pair of free throws to start a 9-0 Jayhawks spurt that erased more than half of the Bears' lead.

Taylor then finished the first half with a 3-pointer from the right wing that brought Kansas within 37-33, and the rest of the lead was gone when Collins converted a spinning layup with his back to the basket just over 2 minutes into the second half.

Reed hit a tiebreaking 3-pointer from the right corner with 9:40 left to put Kansas up for the first time since the opening minute, and Markieff Morris' putback stretched the lead to 58-53 before Dunn got the Bears back on track.

It was the first time in the tournament's 13-year history that Kansas lost its opening game, and the first time that a No. 9 seed had taken down the top seed.