DALLAS (AP) -- Robert Weems scored 18 of his 21 points after halftime and Arkansas ended Baylor's six-game winning streak with an 85-78 victory Saturday night.
Charles Thomas added 17 points, including eight straight for the Razorbacks (11-3) in the go-ahead stretch in the second half when he also drew a charging foul that wiped out an alley-oop dunk for Baylor.
The Bears (11-2) fell short in another bid for a signature victory under coach Scott Drew.
The game was tied at 70 with 6:08 left when Thomas moved in front of a charging Tweety Carter, who passed the ball to Delbert Simpson for a slam. But Carter was called for a foul and the basket wiped out.
Thomas then made two free throws, and stretched Arkansas' lead to 74-70 a minute later when he drove inside for a tough one-handed shot.
Baylor was still within a basket with a minute to go, but leading scorer Curtis Jerrells missed two 3-pointers and Carter came up short on another.
Weems, who had consecutive 3-pointers to tie the game at 55 with about 8 minutes left after Arkansas had fallen behind by nine, made four free throws in the final 19 seconds to clinch the game.
Patrick Beverley had 13 points for the Razorbacks, who started the season in the Top 25 but had lost two of the previous four games. Thomas had 17 rebounds.
Baylor hadn't lost since a 67-64 home loss to No. 4 Washington State on Nov. 30, when the Bears blew a 14-point lead in the second half. The Bears, with victories this year against Wichita State, Notre Dame and South Carolina, led 48-41 at halftime after a 17-4 run over the final 6 minutes.
The Bears, off to their best start since a 12-1 mark in 2000-01, were closing in on a possible Top 25 ranking before losing to Arkansas. It was the schools' first meeting since 1991, when the Razorbacks left the old Southwest Conference.
Drew is in the fifth year of a daunting rebuilding project. He took over after former coach Dave Bliss resigned following a scandal sparked by the slaying of former player Patrick Dennehy by a teammate.
There were NCAA penalties for wrongdoing uncovered during Bliss' tenure that forced the Bears to deal with depleted rosters and limited schedules. Drew and his players had to pay the price even though all the violations occurred before any of them arrived.
Last year, Baylor finally got to play a full regular season with a full roster under Drew and went 15-16.