Coming off its best defensive performance in Big 12 play, No. 23 West Virginia is staring at its most difficult preparation yet for Kansas State's power run offense along with a quarterback mystery.

The Mountaineers (6-3, 4-2 Big 12) entered the AP Top 25 poll for the fourth time this season after holding Iowa State to 350 total yards in a 20-16 win.

West Virginia still has an outside chance to grab one of two spots in the Big 12 championship game but must win out and get some help. The Mountaineers play two of their final three games on the road, starting Saturday against the Wildcats (5-4, 3-3).

Not only must the Mountaineers get ready for an offense that uses its quarterback extensively in its run game, they're not sure which quarterback they'll see.

Third-stringer Skylar Thompson, a redshirt freshman, came off the bench to lead Kansas State to a 42-35 overtime win Saturday at Texas Tech. Backup Alex Delton took a helmet-to-helmet hit and did not play after halftime.

Jesse Ertz has missed several games with a knee injury but is listed first on the team's depth chart this week.

"It's a bigger challenge right now than any team we've faced just because of the unknown," said West Virginia defensive coordinator Tony Gibson. "Who it's going to be?"

Thompson, who was Kansas State's top recruit in 2016, rallied the Wildcats from 11 points down in the fourth quarter. His 1-yard TD run and two-point conversion pass with 42 seconds left in regulation tied the game, and he hit Byron Pringle with an 8-yard scoring pass in overtime.

Despite Thompson's heroics, Kansas State coach Bill Snyder isn't about to reveal who will start against the Mountaineers.

"We've still got a couple of days of practice to define how we want to do that," Snyder said

First, West Virginia's concern is stopping the run overall. Kansas State is third in the Big 12 at 193 yards per game, the same number the Mountaineers are allowing on average each week. Running back Alex Barnes averages a team-high 65 yards. Delton and Ertz are second and third, respectively, in rushing.

"They run their quarterbacks a lot — which Iowa State did not — and then they have the throw game off of it," Gibson said. "If you load up on the quarterback and start bringing safeties downhill to try to help, then they have all the pop passes and all the different looks off of it. They create some issues for you."

After some lapses against Oklahoma State , Baylor and Texas Tech and despite missing several starters due to injury, Gibson and coach Dana Holgorsen are feeling better about the defense, especially the line as a whole. Sophomore defensive end Reese Donahue has 16 tackles over his last three games to nearly double his season total.

Cornerback Hakeem Bailey had a season-high 10 unassisted tackles and four pass breakups in a backup role against Iowa State while redshirt freshman linebacker Dylan Tonkery had a season-best nine unassisted tackles.

"We're a little banged up, but so is everybody else," Holgorsen said. "That's probably the thing I was most proud of last week, especially with our defense because that's where the injury bug has hit a little bit."

___

More college football: http://collegefootball.ap.org and https://twitter.com/AP_Top25