Oklahoma State is just waiting for something good to happen again, perhaps starting this weekend when suspended preseason All-America guard Marcus Smart returns.
Jefferson scored 25 points and the Bears overcame a buzzer-beater that forced overtime Monday night, handing the Cowboys their seventh straight loss 70-64 in the last of three games without Smart.
The Bears (17-9, 5-8 Big 12) won in overtime at home for the second time in three days. Baylor's Brady Heslip hit a tying 3-pointer at the buzzer in regulation in a double-overtime victory against Kansas State on Saturday.
"We just did two of them the other day so it was nothing new to us," said Jefferson, who also had a game-high 13 rebounds. "We had plenty of practice for it."
The Cowboys (16-10, 4-9) can finish no better than .500 in conference but will get Smart back from his three-game suspension for pushing a heckling fan late in a loss at Texas Tech. He returns Saturday at home in the rematch with the Red Raiders.
Markel Brown and Phil Brown tried to make up for Smart's absence. Brown scored 26 points and Forte, Smart's high school teammate in the Dallas area, added 20.
"We've been playing tough the last two games and Marcus is a tough guy and he's ready to get back on this court," Brown said. "He's been watching the games on TV.
Isaiah Austin had 12 points and 12 rebounds for the Bears, who won for the fourth time in six games in a run that started with a win at Oklahoma State that snapped a five-game skid.
This was supposed to be a high-profile Monday matchup between a pair of teams that were 12-1 and ranked in the top 10 nationally when Big 12 play started. Instead, it was a battle for postseason survival, and played out that way.
Baylor, which trailed by 10 early in the second half, went ahead 56-55 on a dunk by Jefferson after a missed free throw by Austin and was up by three and had the ball with 3.5 seconds left.
But Gary Franklin's inbound pass was intercepted by Leyton Hammonds, who dribbled around a defender and hit a 3-pointer at the buzzer to force overtime at 58-all. It was Hammonds' first 3 since the season opener.
"It was almost like the basketball gods wanted us to win," Brown said. "Then they took it back away from us."
Jefferson made a 3-pointer from the left wing to start overtime and put Baylor ahead for good.
The Bears missed some free throws early in the extra period to give the Cowboys a chance to stay close, and they got within two on a 3-pointer by Brown.
But Kenny Chery made a driving layup for a four-point lead with less a minute left, and Brown missed a 3 at the other end.
The Bears shot 38 percent but made three of four shots and outscored Oklahoma State 12-6 in overtime. They had a 19-5 edge in the second extra period against Kansas State.
"I was really, really proud of how our guys came out in the overtime because when you do something like that, it's devastating," Baylor coach Scott Drew said. "That's like getting punched in the gut. You're hunched over and for us to refocus ... I thought it was tremendous."
The Cowboys went up 10 early in the second half on a 3-pointer by Forte, who was scoreless in a home loss to Baylor earlier in the month. The Bears rallied and went ahead on a dunk by Austin with 5 minutes remaining.
Forte put Oklahoma State ahead 55-54 on a 3-pointer, but Hammonds' tying shot was the only basket for the Cowboys in the final 3 minutes of regulation and the first 3 1/2 minutes of overtime.
Brown and Forte were the only Oklahoma State players with more than six points.
"There's no reason we should have been in the game other than fight, other than effort, other than will," Cowboys coach Travis Ford said. "We've got two players out there that were scoring."
Baylor stayed close in regulation with a huge edge in offensive rebounding and some tenacious defense that included consecutive shot-clock violations by the Cowboys, who shot 37 percent.