Thirty-one seconds into a Virginia A Division 2 girls’ basketball quarterfinal Saturday afternoon, George Mason Coach LaBryan Thomas called a timeout. The Mustangs had just given up a three-pointer, and he had seen enough during that half-minute to know this was not his usual team on the floor.

After the brief, attention-grabbing tune-up, George Mason rolled to a 68-35 win over Northumberland at Robinson to advance to the state semifinals at the Siegel Center in Richmond, where the Falls Church school will face Floyd County at 10:30 a.m. Friday.

The Mustangs, who returned only one starter from last year’s state championship team, are vying for their fourth crown in five years. In Thomas’s view, they did not resemble contenders during that first 31 seconds Saturday.

“He said, ‘This isn’t you. Refocus and play your game. Or else we’re going home,’ ” sophomore forward Katie Goodwin said after the game.

“We spend a lot of time on our defense,” Thomas said, “and when I see something that’s not right, I’m going to quickly address it and change it around. After I called that timeout and addressed the issue, we started playing. We were just being lazy, not hustling back.”

Stephanie Cheney, pictured during last year’s state championship game, led George Mason back to the Virginia A Division 2 semifinals with 25 points and 17 rebounds in a 68-35 win over Northumberland. (Tracy A. Woodward/THE WASHINGTON POST)

George Mason (25-5) responded by quickly taking a 14-point lead, and it was a 22-point game by halftime, with the Mustangs well on their way to a 14th consecutive win.

Northumberland, from Heathsville, Va., missed 24 of 29 shots in the first half. During that same time, seven Mustangs scored. For the game, Northumberland missed 53 of 64 shots, and George Mason’s recalibrated defense had something to do with that inaccuracy.

“We weren’t talking on defense, and that’s what fuels our offense,” said senior forward Stephanie Cheney, who finished with 25 points and 17 rebounds. “Our warmup didn’t seem as high intensity today. We kind of had to readjust mentally, and that’s one of our strongest aspects as a team, that we come out strong at the beginning of the game and tend to get a lead early.”

Besides the typical standout performance from Cheney, a Penn recruit who became George Mason’s all-time leading scorer last season, the Mustangs got 12 points and nine rebounds from Goodwin, another first-team all-Bull Run District choice. Junior guard Jaya Chavern added 10 points.

“When you get to this point and everybody’s playing together,” Thomas said, “it’s tough to beat us.”