Chantilly quarterback Sonny Romine suddenly reversed field, the end zone less than 10 yards downfield and the clock less than 20 seconds from expiring Friday night at Chantilly. The Charger trailed Oakton by seven points, and Cougars linebacker C.J. Reimann turned to pursue with the worst thoughts in his head.

“Anytime you see No. 6 for Chantilly scrambling it’s always a little heart wrenching,” Reimann said. “Because you know he’s a playmaker.”

As Romine turned the corner, however, senior linebacker Michael Durst met him and knocked the ball lose, and Reimann recovered the fumble to preserve Oakton’s 21-14 win — and its undefeated record — on the road.

It was Chantilly’s eighth fumble of the night and the third that Oakton’s defense recovered in a bounce-back performance after giving up 41 points in a one-point winlast week over Herndon.

“It’s huge,” Durst said. “We responded great. We played as a team, we stayed together and that’s what did it for us.”

Oakton’s offense struggled early, going three and out on its first two possessions and losing a fumble after a 45-yard reception to end the third. Meantime, Chantilly took a 7-0 lead on its first drive of the night.

The Cougars (7-0, 2-0 AAA Concorde) hit their stride behind their run game, gaining 150 yards and two touchdowns before halftime — led by quarterback Tuck Masker’s 45 yards and two scores and 46 yards from Kelly Brooks-Muse. Masker had runs from one- and four-yards out to cap 10- and 12-play drives.

“We always preach getting off to a fast start and if that doesn’t happen you’re facing adversity,” Masker said. “And we talked about facing adversity throughout the entire offseason. And if we find any spark, any air to breathe, we’re gone.”

Stephen Lambrides’s 36-yard touchdown catch put Oakton up 21-7 with 4 minutes 53 seconds remaining in the third quarter, but Chantilly fought back.

Romine hit Jimmy Hicks for a 30-yard score on fourth and seven with 5:04 left in the game, and it looked like the Chargers (5-2, 0-2) had more magic left. Durst’s play in the closing seconds proved otherwise.

“It feels great to be 7-0 right now,” Reimann said. “But we’ve got a really good Westfield team [also 7-0] coming to our place next week and . . . it’s going to be a battle of the unbeatens. One of us has to come out with a win and one in the loss column, and I hope it’s not us.”