AUSTIN, Texas -- With Oklahoma State's national-leading offense stuck in neutral by the play of Texas' smash-mouth, bend-but-don't-break defense, it was up to someone on the other side of the ball to make a winning play for the 10th-ranked Cowboys.

Cue Oklahoma State safety Ramon Richards.

He intercepted a pass from Texas quarterback Sam Ehlinger in the end zone in overtime to give the Cowboys a hard-fought 13-10 win at Darrell K Royal-Texas Memorial Stadium on Saturday in a defense-first Big 12 Conference battle.

"It was a game filled with mistakes, other than on defense," Oklahoma State coach Mike Gundy said. "As long as I've been head coach, I've never seen our defense play like that, on the road and dealing with all the adversity."

Oklahoma State took the lead in overtime with a 34-yard field goal by Matt Ammendola, who missed from 29 yards late in regulation. Texas, in field goal range to tie the game at the Cowboys' 6, got greedy as Ehlinger tried to lob a pass to Jerrod Heard, who had been bumped off his route and out of bounds, leaving Richards in position to haul in the interception.

"When Ramon went up, I knew he would make that interception because he's a former quarterback and it was kind of a soft pass," Gundy said. "I didn't know I had been living so good. We are going to shower as fast as we can and pack up and get on the bus and get on the plane before somebody changes their minds and we have to play again."

Richards didn't immediately realize his play clinched the game for Oklahoma State.

"I thought the offense had to come back," Richards said. "Then I saw everyone rush the field. Oh, it feels great."

The Cowboys (6-1, 3-1 Big 12) entered the game atop the FBS rankings for total offense, averaging almost 611 yards and 49 points per outing, but they were stymied by a Texas defense that was hell-bent on stopping the pass and especially the deep strike, the tactic that's pushed Oklahoma State into the upper-echelon of college football.

Oklahoma State quarterback Mason Rudolph, who led the nation before Saturday with a 394.7-yard passing average, managed just 282 in the win, 66 of which came on a pass to Marcell Ateman early in the fourth quarter when Texas defender Brandon Jones tripped over his own feet in coverage.

"A monumental effort by our defense. To hold the No. 1 team in the country to 10 points in regulation is something to be proud of," Longhorns coach Tom Herman said. "We gotta help them more on offense; we've got to fix what's wrong. We have flashes but we are not consistent enough."

It was Texas' third overtime game this season. The Longhorns (3-4, 2-2) lost 27-24 at USC on Sept. 16 and beat Kansas State 40-34 at home on Oct. 7.

Oklahoma State got the scoring started with a 7-yard run by J.D. King at the 4:51 mark of the first quarter that culminated a 96-yard march in 10 plays.

A fumble by running back Justice Hill at the Texas 14 early in the second quarter denied the Cowboys another scoring chance.

Texas quickly took advantage. Ehlinger (22 of 36, 241 yards) hit John Burt on a 90-yard catch-and-run against the right sideline that moved the Longhorns to the 2-yard line. Ehlinger powered his way into the end zone on the following snap to tie the game at 7 with 13:59 to play before halftime.

Oklahoma State outgained the Longhorns 428-283, with the majority of the advantage coming in a 146-42 edge in rushing. Texas got 90 of its total yards on one pass or things would have been much more lopsided in the statistics, if not the scoreboard.

The Longhorns took the second-half kickoff and drove 71 yards in 13 plays but had to settle for a 22-yard field goal by Joshua Rowland and a 10-7 lead.

The Cowboys countered with a 12-play, 74-yard drive that ended with Ammendola's 19-yard field goal with 12:31 to play in the fourth quarter that tied the game at 10. But even that score was tempered by the fact that Oklahoma State had a first-and-goal situation from the Texas 1-yard line and was pushed back a yard in three subsequent snaps.

The 66-yard pass from Rudolph to Ateman set up the Cowboys for a 29-yard field goal attempt with 4:15 remaining in the fourth quarter but Ammendola pushed the kick wide right, setting the table for overtime -- and, ultimately, heartbreak for the Longhorns.

"We're not really worried about our record," Texas cornerback Holton Hill said. "We will focus on our next opponent and going into them 100 percent, full-speed and working on execute our jobs."

NOTES: Texas' youth has shined through in the starting lineup. The Longhorns' last two recruiting classes (true freshmen, redshirt freshmen and true sophomores) have combined to make 41 starts this season, including 34 on offense. ... Saturday's game marked the third time in five contests that Texas played an opponent ranked inside the top 12 in the polls. ... Oklahoma State QB Mason Rudolph entered the game with 24 completions of more than 30 yards, leading the nation in that category. He had one on Saturday.