The Robinson and Chantilly volleyball teams spent much of yesterday's Northern Region quarterfinal yanking the momentum back and forth across the net. But midway through the decisive fifth game, Robinson senior setter Missy Rachel sensed the tide building on her side of the court, and she liked the feeling.

"You can tell -- the timing starts to click, the passing gets better, you can start to run plays," Rachel said. "It makes it a lot more fun, and that's when our game picks up."

Riding that wave, the Rams closed with seven consecutive points, earning a 15-10, 18-16, 9-15, 10-15, 15-8 victory and a berth in the region semifinals. Robinson (19-3), the Patriot District's regular season and tournament champions, will play No. 4 Westfield on Thursday for a berth in the state quarterfinals. The Bulldogs beat Mount Vernon, 15-6, 15-1, 15-6.

Junior outside hitter Tricia Nelsen, a converted middle blocker, keyed the Rams' final run with four of her 15 kills. Nelsen was one of four Rams who finished with at least 14 kills, led by senior Nicole Vetock with 17. Rachel had 40 assists.

Robinson won despite a superb effort from Chantilly junior Kate Wooldridge. The Concorde District MVP slammed 43 kills, many of them from the back row, as the Chargers (14-5) climbed their way back from two games down.

The early deficit "didn't help, but we used that energy and just pushed it as hard as we could," Wooldridge said. "I'm really proud of our team for making it this far."

Robinson Coach Tracy Ferguson said she welcomed the opportunity to compete with the region's strongest district, which has produced five of the last six region finalists.

"They've earned all the stripes, so if we want any stripes we have to go get them," Ferguson said. "If we want to be the best, we've got to beat the best."

Centreville will play Herndon in Thursday's other semifinal.

Centreville advanced with a 15-13, 15-10, 15-5 victory over visiting West Potomac in Clifton. Christi Moot had 15 kills, and Mary Dorula and Rebecca LaBrake had nine kills apiece, while setter Stephanie McKee had 32 assists.

Middle blockers Lucy Bawick and Britany Westphal paced Herndon to a 15-5, 12-15, 15-7, 15-12 victory over Lake Braddock in Burke.