Jaguars hand third ranked Cougars first loss of the season, 35-21. (Andrew Kloc/The Washington Post)

During the week of film study devoted to Friday’s showdown with Montgomery 4A West rival Quince Orchard, Northwest Coach Mike Neubeiser noticed a peculiar trend.

More than once, the players corrected Neubieser and his staff as they identified their Cougars’ counterparts on tape. And more often than not, their scrutinies were spot on.

That shouldn’t be surprising. The two schools are separated by just five miles, and many of the athletes have tussled on a football field since they were knee high to a water cooler.

The Jaguars’ familiarity with their previously unbeaten foe helped spur a 35-21 upset win over the No.3 Cougars Friday night in Gaithersburg.

“They didn’t see it as Quince Orchard — one of the best teams in the state — they saw it as Quince Orchard, the kids they grew up playing against,” Neubeiser said. “And I think that made a big difference with their confidence.”

Friday’s upending marked the Cougars’ first regular season defeat since Sept. 28, 2012, when they dropped a 12-9 game to Seneca Valley. It’s the first time an opponent has put up 35 points on Quince Orchard (8-1, 3-1 Montgomery 4A West) since the 2011 state title game (a 36-35 loss to Old Mill).

Northwest sophomore quarterback Mark Pierce tossed four touchdowns, with receivers Joshua Gills and Matt Watson each hauling in a pair of scores.

“[Mark] did a great job,” Neubeiser said. “He was poised and had time to sit back and read the field. He’s an excellent timing passer.”

Gills made his catches count despite a constant shadow from Quince Orchard’s Elliot Davis — the Jaguars top defensive back and a coveted Football Bowl Subdivision recruit.

“There’s not too many guys who can cover [Gills or Watson] one-on-one,” Neubeiser said.

A standing-room only crowd showed up in Gaithersburg for the neighborhood grudge match. While a 22-point Jaguar lead early in the fourth quarter might have suppressed a lesser fan base, Quince Orchard’s “Red Army” student cheering section kept its foot on the decibel pedal even in defeat.

“I would love to see the number of people who were at the game,” Neubeiser said. “The entire way around the track it was packed.”

Northwest (7-2, 2-2) can clinch third place in 4A West with a win over Springbrook next week.