MORGANTOWN, W.Va. -- Backup quarterback J.W. Walsh scored on a fourth-down keeper in overtime and No. 21 Oklahoma State beat West Virginia 33-26 in a Big 12 matchup Saturday night to continue its run of late-game drama.

Oklahoma State (6-0, 3-0) was in danger of losing to West Virginia for the third straight season after blowing a 15-point halftime lead. But the Cowboys survived, just as they did against Texas and Kansas State.

"We've had these games the last three weeks where we've had to win at the end," said Walsh, also threw a 4-yard touchdown pass to Blake Jarwin as part of Oklahoma State's short-yardage package. "To come into Morgantown in a night game against a very good West Virginia team with a win, it doesn't matter how we got it. When you watch the game over, you'll see how tough we are."

West Virginia quarterback Skyler Howard, who ran 3 yards for a touchdown with 2:44 left in regulation to tie the score at 26, saw his fourth-and-11 pass in overtime fall incomplete in the end zone.

Running back Wendell Smallwood overcame a sore ankle to run for 147 yards on 19 carries, including a 29-yard score, for the Mountaineers (3-2, 0-2), who are in the midst of a four-game stretch against ranked teams. Their next two games at No. 3 Baylor and No. 2 TCU could portend an 0-for-October after breezing through the nonconference schedule.

Opponents had gone 0 of 8 on fourth-down tries against West Virginia this season until Cowboys coach Mike Gundy kept Walsh and the offense on the field in overtime. The fourth-and-1 play from the 2 gave Walsh a small gap up the middle.

"Exactly how we drew it up," Gundy said. "We practiced that play and repped it all week."

Nose guard Kyle Rose thought the Mountaineers had the play scouted -- until Walsh plunged in.

"We knew he was going to run it. On fourth down, you've got to man up, and we just didn't," Rose said. "Every time we want that on our shoulders. We could've held them and the offense could've come out, kicked a field goal and won the game."

Howard's 48-yard strike to Shelton Gibson midway through the third quarter drew West Virginia within 23-16. But Howard, who finished 18-of-35 passing for 188 yards, also committed two turnovers that gave Oklahoma State 10 points.

"I've got to be better," Howard said.

After Walsh's third-quarter scoring pass, Oklahoma State bobbled the point-after snap, a crucial mistake as the game inched toward overtime.

The Cowboys survived three interceptions by quarterback Mason Rudolph, who completed 20 of 40 passes for 218 yards.

West Virginia was stung by three first-half turnovers, one created on a backfield collision between Smallwood and Howard that led to a touchdown fumble recovery by Emmanuel Ogbah.

Oklahoma State's lead swelled to 14-0 on Rennie Childs' 1-yard score, the result of a 28-yard drive after West Virginia's Rushel Shell fumbled.

Smallwood also lost a fumble inside the Cowboys' 10, but Rose sacked Rudolph for a safety on Oklahoma State's next snap.

Ben Grogan's 21-yard field goal made it 17-2 after Gundy opted against a fourth-and-1 try at the West Virginia 4.

Starting four first-half possessions inside its own 12, West Virginia's offense was held scoreless in a half for the first time this season.

The Mountaineers recovered to finish with 443 yards, the most allowed by Oklahoma State this season, though the stat didn't concern Gundy.

"The momentum was on their side in the fourth quarter," Gundy said. "We were tired on defense. West Virginia tempoed us. They fatigued us some. But our guys were able to rally at the end and make a play."

NOTES: West Virginia RB Wendell Smallwood topped 100 yards rushing for the third straight game but wasn’t on the field in overtime. ... Despite leading the Big 12 in overall red-zone scoring percentage, Oklahoma State ranked seventh in red-zone touchdown percentage. West Virginia came in leading the conference in red-zone touchdown defense. ... West Virginia is 0-5 against ranked Big 12 teams at night since joining the Big 12 in 2012 and 0-6 in Big 12 night games overall. ... Oklahoma State, which leads the nation in sacks and tackles for loss, dropped Rushel Shell for a 7-yard loss on the next-to-last play in overtime. ... For the first time in 43 games, West Virginia played without safety Karl Joseph, who tore an ACL in practice this week and was ruled out for the season.