Nebraska senior guard Lance Jeter's 17 points were a big part of the reason the Cornhuskers had a chance to win with 10 seconds left.
But given the opportunity to make the final play, Jeter slipped as he drove into the paint and the ball helplessly skittered away as the buzzer sounded.
But the day belonged to an Oklahoma State team that started hot and hit almost 47 percent of its three-point attempts. Keiton Page made four of his eight shots from distance and scored 16 points, while Marshall Moses brawled his way to 10 points inside.
Nebraska, which entered the Big 12 Tournament on the outside looking in, probably cemented its fate with the loss, dropping the Cornhuskers' record to 19-12. Oklahoma State moved up to 19-12 and will play Kansas in the early game at 11:30 Thursday.
In a duel between two explosive guards, Alec Burks led his Buffaloes just past Jake Anderson's Cyclones.
That victory didn't come through a lack of effort from his counterpart. Anderson was brilliant for most of the night, hitting 13-of-20 shots and scoring 33 points while grabbing six rebounds. Supported by 19 points and six assists from point guard Diante Garrett, the Cyclones held a small lead at halftime, then kept the lead for most of the second stanza.
But they couldn't keep down Burks, who scored 29 points, grabbed 15 rebounds, dished out six assists and had three steals. Burks continually penetrated into the heart of the Cyclone defense, and his hanging shot gave the Buffaloes a late lead they didn't relinquish. Cory Higgins chipped in 16 points and four rebounds, while Levi Knutson scored 12 and made several key shots in the comeback.
Colorado (20-12) helped its situation on the bubble with the win. The Buffaloes will play Kansas State at 2 p.m. Thursday. Iowa State finished 16-16.
Oklahoma 84, Baylor 67
The Sooners' solid defeat of the Bears came as one of the opening day's biggest surprises. Buoyed by the absence of Bear forward Perry Jones III, who was declared ineligible, the Sooners used a 19-2 run to jump ahead early and were never seriously challenged again.
Cade Davis poured in 24 points, the fifth time in six games that he has topped the 20-point mark, and the Sooners shot almost 58 percent from the field. Meanwhile, Davis and fellow guard Steven Pledger limited Lacedarius Dunn, the Big 12's career scoring leader, to a 3-for-14 shooting night.
Quincy Acy led the Bears with 21 points and 15 rebounds, but it wasn't enough to make up for his teammates' struggles.
Three Sooners besides Davis scored 10 or more points, with Carl Blair finishing with 18 points, 11 assists and six rebounds.
Oklahoma (14-17) will move on to play Texas, which thumped the Sooners in two previous outings. That game is scheduled for 6 p.m. Baylor's loss knocked the Bears to 18-13 on the year, and likely burst the Bears' tournament bubble.
In the first day's final game, the Tigers held off multiple Red Raider rallies to sneak out with a four-point win.
Missouri won the first half 48-44, then appeared to have the game in hand at multiple points in the second half, pushing that advantage into the double digits. But the combination of a comedy of Missouri errors and a monster 28-point outing from Tech guard John Roberson kept the Red Raiders within striking range.
Tech trailed by two multiple times within the final two minutes, but never were able to take the lead back. The Tigers were paced by 20 points from Marcus Denmon, 17 points and four assists from surprise starter Michael Dixon and 15 from Kim English, including several clutch free throws.
Missouri (23-9) will play Texas A&M in the late game Thursday. At 13-19, Texas Tech's season is likely over.