STILLWATER, Okla. -- Drafted by the New York Yankees in the second round, Brandon Weeden was a starting pitcher all the way.

After giving up baseball, the strong-armed right-hander earned perhaps his biggest win as an ace reliever.

Weeden, the third-string quarterback for No. 12 Oklahoma State, threw for 168 yards and two touchdowns in the second half to lead the Cowboys back from an 11-point deficit for a 31-28 win against Colorado on Thursday night.

"Right when we came out from halftime, I just kind of got a couple snaps, threw about five or six passes and I was throwing fire," Weeden said. "I like that. I really do. I think that's fun."

With starter Zac Robinson injured and backup Alex Cate ineffective, the Cowboys (9-2, 6-1 Big 12) turned to Weeden to spark the offense.

His 28-yard touchdown pass to Justin Blackmon with 8:11 remaining proved to be the winner, keeping pressure on No. 3 Texas in the Big 12 championship race. The Longhorns would have clinched the Big 12 South with an OSU loss.

"We kept on giving him the 1-ball, and he kept throwing the heater, and finally we made a catch or two -- and he made some plays with his feet, too," offensive coordinator Gunter Brewer said.

Colorado got out to a 21-10 lead against the one-dimensional Cowboys before Weeden finally provided a viable passing threat. He went 10 for 15 and threw a 47-yard touchdown pass to Keith Toston.

Weeden had to give up baseball when he started having problems with his pitching shoulder and he can't explain why it doesn't affect him nearly as much when throwing a football.

The lessons the 26-year-old learned during five years in the minor leagues -- never rising higher than Class-A -- paid off in his first big chance on the college football stage.

"Not necessarily my age but I think baseball really helped me out. Being 18 years old and basically you're just thrown in the fire," Weeden said. "Move halfway across the country and they said, `Here's a baseball. Go throw it.' Really and truly.

"Just having to grow up and learn that on the fly on my own, I think that's helped me not only in football but in life."

The Buffaloes (3-8, 2-5) had one final chance to go for the win after stuffing OSU on fourth-and-short for the third time in the game with 3:14 remaining but decided to punt after Tyler Hansen threw three straight incomplete passes. The Cowboys, the Big 12's top rushing team, ran the final 2:45 off the clock.

Oklahoma State wore black uniforms for the first time since 1994 -- a miserable 3-7-1 season -- and they didn't seem to be a good luck charm in the team's first Thursday night home game since 1995.

Cate, who had attempted only five passes in his career, started in Robinson's place but went 0-for-9 with an interception in the first half - and it could have been worse. Colorado players had chances for at least two more picks, but let the ball slip through their hands.

Weeden came on in relief and connected on his first pass before throwing three straight incompletions for a three-and-out. When he completed back-to-back passes on OSU's third drive of the third quarter, the crowd of 50,080 let out Bronx cheers.

Two plays later, Toston finished that drive with a 45-yard touchdown run through a huge hole on the right side of the line to cut the deficit to 21-17.

Colorado had a chance to stretch its lead, but Aric Goodman's 50-yard field goal try caromed off the right upright and coach Dan Hawkins then opted to go for it on fourth-and-3 from the 29-yard line instead of sending Goodman out to try a 46-yard kick.

"We all knew as a team that if we got that fourth down, we were going to score and seal the game. There was no hesitation, we were going for it," said Hansen, who threw incomplete to Riar Geer on the play. "I was going to the sideline saying we're going for it."

Oklahoma State came right back on its next possession to take the lead on Toston's 47-yard touchdown catch. Toston released out of the backfield, ran between two blitzing defenders and caught a short pass from Weeden before racing into the end zone for the go-ahead score.

Brian Lockridge answered with a 98-yard return for a touchdown on the ensuing kickoff to put the Buffaloes back ahead with 11:11 remaining, but Weeden responded with two big completions on third-and-long before finding Blackmon in the end zone as he scrambled to the right.

"Obviously, he's blessed by his arm or he wouldn't have been in pro baseball. He delivered some balls and we made some plays," Brewer said.

It was only the second win for OSU against Colorado in the teams' last eight meetings in Stillwater. Both teams ended up playing switcheroo at quarterback, with Cate getting a 7-0 head start when Perrish Cox brought back Matt DiLallo's first punt 67 yards for a score.

OSU's defense then sacked Hansen on back-to-back plays to force a three-and-out, but Toston took a handoff from Cate on the Cowboys' first offensive snap and fumbled for the first time in 287 carries -- a span of more than two years since he'd been benched for fumble problems in September 2007.

Hansen capitalized with a 5-yard touchdown pass to Scotty McKnight before leaving briefly with a thumb injury. Cody Hawkins, the former Buffaloes starter and the coach's son, replaced him and threw a 5-yard score to Geer to put Colorado up 14-10 at halftime.