The key to the South County softball team’s dominance of Conference 7 this season has been consistency. The second-ranked Stallions have mostly the same roster as last year, save for one graduated senior and some junior varsity additions.

And despite a recent shake-up of their batting order, South County’s stalwarts played a key role Monday night in a 4-1 victory in a Virginia 6A North region quarterfinal at No. 9 McLean, snapping the Highlanders’ 18-game winning streak.

Senior pitcher Rebecca Martin struck out six to help lift South County (22-3) to a meeting with conference rival West Potomac in a region semifinal on Wednesday.

It was about six games ago when Stallions Coach Gary Dillow tweaked the lineup — an unusual switch for a squad that had rarely altered a winning formula in four years.

“We were in kind of a lull — Rebecca was pitching great, but we weren’t hitting,” Dillow said.

The new batting order bumped Martin from seventh to first, and shifted the rest of the squad down a notch.

On Monday, Martin’s single in the top of the third inning was part of a stretch that included a single from Mollie Maglich, a walk by Carley Kastner and a single from Caitlin Maglich to score South County’s first run.

The next three runs came in the top of the sixth on a Riley Wilkinson double to center field, followed by back-to-back home runs from Haylea Geer and Jade Williams.

McLean’s run came in the bottom of the sixth on a home run by Olivia Bravo.

The two teams had the highest scoring games in the first round of the tournament, and the Stallions have scored double-digit runs in nearly half of their games this season.

McLean starter Maddy Witchey kept her team in the game but ultimately they fell short.

“We know we can go far in playoffs if we put our minds to it,” Geer said. “And right now, we’re playing to the best of our abilities.”

The Stallions will host Conference 7 rival West Potomac, which beat Fairfax 7-1, in Wednesday’s semifinals.

Elsewhere in the 6A North, Lake Braddock walked off with a wild, 13-inning, 2-1 victory over Madison that lasted more than three hours. The Bruins will host Langley — a 3-0 winner over Patriot — in Wednesday’s other semifinal.

In the 5A North region quarterfinals, Forest Park defeated Franklin County to earn a semifinal date with Cosby, which topped Woodbridge, 4-1. . . .

Madison Goodman pitched a complete game four-hitter to lead Briar Woods to a 2-0 shutout win over Massaponax in a 5A North region quarterfinal. Stone Bridge earned a 5-3 win against North Stafford and will face Patrick Henry-Ashland, which dispatched Tuscarora 11-1, in Wednesday’s semifinals. . . .

In the 4A North, Woodgrove blanked Liberty 5-0 to earn a semifinal matchup with Louisa County, a 10-2 winner over Carroll County. Loudoun County fell 3-0 at Fauquier.