AUSTIN, Texas (AP) - Six straight wins had put No. 23 Texas back in the polls, in control of its Big 12 destiny and tempered speculation that Mack Brown's job was on the line.
The worst home loss in Brown's 16 years at Texas just undid all of that.
Case McCoy threw for 221 yards but had three interceptions and No. 12 Oklahoma State beat the Longhorns 38-13 on Saturday. The blowout dealt Texas its worst loss at home under Brown and did so at a time when questions over his job security had just begun quieting down amid a midseason resurgence.
But in getting clobbered by the Cowboys, the Longhorns looked more like the shaky team that fired its defensive coordinator between early losses to BYU and Ole Miss before turning things around. Now they'll have to do so again but with just two games left, including playing at No. 4 Baylor.
''I'm disappointed,'' Brown said. ''I don't get stunned about anything anymore.''
A resurgent Texas had just returned to the Top 25 after a two-month absence. Now the Longhorns (7-3, 6-1) are almost certain to fall unranked again, but more costly in this blowout was relinquishing control of their destiny in the Big 12.
Oklahoma State quarterback Clint Chelf ran for two touchdowns and threw for two more as the Cowboys (9-1, 6-1) won in Austin for the third straight time. They've now pulled off six straight wins since an early stumble against West Virginia, and have kept looking like the Big 12 contenders that many predicted to start the season.
''We understand how big the game is. I'm not sure if at times everybody wants to say that that's a heck of a win, but it is what it is,'' Oklahoma State coach Mike Gundy said. ''You very seldom go on the road and win by more than three touchdowns with teams that are undefeated in conference play in the middle of November.''
Oklahoma State still has yet to face undefeated Baylor, which was playing Texas Tech later Saturday. The Cowboys host the Bears next week.
Chelf threw for 197 yards and an interception. He was also Oklahoma State's leading rusher, running for 95 yards that were largely piled up with long sprints from the shotgun that cut through the middle of the Texas defense.
Texas running back Malcolm Brown ran for 79 yards and a touchdown.
Texas' previous worst loss at home under Brown was a 34-12 defeat by UCLA in 2010. The Longhorns now have now been blown out at home twice this season after losing 44-23 to Ole Miss in September.
A close first half turned into a runaway behind two near-misses by Texas in a span of less than a minute. First up was Texas safety Adrian Phillips missing a would-be interception in the end zone, with the ball ricocheting off his hands and into the arms of Tracy Moore for an Oklahoma State touchdown.
Even more deflating for Texas was the ensuing Texas drive, when Cowboys safety Justin Gilbert picked off McCoy just 18 seconds before halftime and returned it 43 yards for another score.
McCoy finished 26 for 39 for 221 yards and would throw two more interceptions. Linebacker Caleb Lavey picked off one of them, running it back to Texas' 21 to set up a Chelf touchdown pass to Charlie Moore on the very next play.
''The quarterback goes out and throws three picks, you're not going to win the ballgame,'' McCoy said. ''It's very rare that happens. So it's on me, my team knows it's on me, and we're going to get it fixed and go win.''
Charlie Moore led all Oklahoma State receivers with six catches for 83 yards.
Oklahoma State played without leading wide receiver Josh Stewart, who didn't make the trip after appearing to injure his left leg in a win over Kansas last week. Stewart is also the nation's leading punt returner, but aside from understudy David Glidden bobbling a few catches, the Cowboys hardly noticed his absence.
On hand to watch Brown's worst loss ever at Royal Memorial Stadium was new athletic director Steve Patterson, who was hired from Arizona State earlier this month to replace DeLoss Dodds. Patterson has said he doesn't intend to ''make change just for the sake of making changes'' as he takes over the nation's wealthiest athletic department.
Brown began the season talking about Texas being ready to compete for a national title again after a run of uneven seasons since losing to Alabama in the title game in 2009. But the Longhorns instead started out by losing badly to BYU on the road and getting blown out at home by Ole Miss.
Speculation about Brown's future intensified after revelations that the agent of Alabama coach Nick Saban had talked to University of Texas regents a few days after the Crimson Tide won the national championship last season.
Follow Paul J. Weber on Twitter: www.twitter.com/pauljweber