The Lake Braddock Bruins stun the Stone Bridge Bulldogs 31-26. (Tyler Stevens/The Washington Post)

If it were up to Trevor O’Brien, Lake Braddock’s season opener would have been his coming-out party, a time when he could stake his claim as the Bruins’ new starting tailback while dusting off any rust in anticipation for Friday’s big game at No. 3 Stone Bridge.

A pass-heavy attack in last week’s game altered O’Brien’s plan, but with the Bruins in need of a gritty performance against the oversized Bulldogs, the 5-foot-9 senior answered the toll, rushing for 116 yards and three touchdowns as No. 11 Lake Braddock knocked off Stone Bridge, 31-26, on the road in Ashburn.

“When the season ended and we all got back to work in the weight room, the coaches told me the running back spot was mine, but I didn’t take that for granted, and I worked for this moment,” O’Brien said. “I said if they weren’t going to respect the run, then I’d be ready, and with the [offensive] line blocking, we got it done.”

All week long, the Bruins had caught glimpses of the physically imposing team they would face, and on the Bulldogs’ first play from scrimmage they got another reminder. Sterling Dailey burst through a hole created by Stone Bridge’s hulking offensive linemen and zoomed 65 yards to put his team up 7-0 just two minutes into the contest.

But the Bruins responded by pushing the tempo with a no-huddle spread attack that tested Stone Bridge’s endurance in its first game of the season. O’Brien scored on a 27-yard run, and in the second quarter, Caleb Henderson lofted a 30-yard pass in the end zone to A.J. Alexander, who extended for an acrobatic touchdown catch. By the time O’Brien scored his second touchdown of the night on a four-yard run midway through the second quarter, the Bruins appeared in control while Stone Bridge’s offense sputtered behind two turnovers.

“We wanted to get after them with a faster pace and test their conditioning, and you saw it pay off toward the end with their guys cramping up and fatigued,” Bruins Coach Jim Poythress said. “But there’s a reason they have the success they have, so we knew they would keep fighting.”

Using a more methodical pace, Stone Bridge began the second half with a 13-play drive that chewed up more than seven minutes and ended with Dailey (161 rushing yards) scoring the second of his three touchdowns to cut the deficit to 21-14. But once the Bruins regained possession, they again pushed the tempo, extending the lead on a Cory Huddleston field goal and another O’Brien touchdown.

Stone Bridge threatened with an 80-yard touchdown pass from Joe Thompson to Chance Frye and another Dailey score in the fourth quarter, but the Bruins’ defense held strong with sack by Kevin Hankton on fourth down and a late interception by Alexander.

The loss, in the first meeting between the Bruins and Bulldogs, was Stone Bridge’s first to an area team since a 22-14 defeat at Chantilly on Sept. 10, 2011.