Jonathan Law showed why it had advanced to the Class M state semifinal round with a rousing come-from-behind 25-21 victory in the first set of its match with Weston High in Fairfield on Tuesday night.

The Trojans kept feeding its middle hitters — Katie Anderson and Eliza Maestri — and swept the next three sets to earn a berth in the finals where they will play unbeaten Seymour High at East Haven High on Saturday at 4.

“Yesterday, we put a big chair in the middle and asked the girls ‘What are you going to do?,’” Law coach Stacy Loch said about the challenge of preparing for the 6-4 Anderson and her 6-2 sidekick Abby Glasberg. ‘How are you going to adjust?’”

Reality won over theory, as Anderson finished with 17 kills, Maestri 15 kills and Glasberg was a force with four blocks in Weston’s 21-25, 25-17, 25-20, 25-19 victory.

“Law gave us a run for our money,” Weston coach Mackenzie Robens said after her No. 18 seeded squad improved to 16-8. “A focus for us was our defense at the net against them. In the end our blockers came through.”

The No. 11 seed Lady Lawmen (18-6) were led by Madi Lula (10 kills), Katie Eighmy (5 kills, 6 digs), Pam Ellison (10 digs, 3 aces), Caroline Chesson (3 kills), Eryn Mower (12 assists) and Olivia Kowalski (10 assists).

“There were so many things,” Loch answered when asked what stood out for her team. “We played great defense, then were taken down but picked it right back up. We were resilient and turned it around in each game. Weston just played so well.”

Game one was tied three times in the first service rotation, including 11-11.

Anderson, a junior, kept adjusting her strike angles to carry the Trojans.

It took a fine service game by the Lady Lawmen’s Emiley Morey, who had her team’s third ace in a three-point run, to make it 22-19 Law.

An Eighmy kill, and then an Alexis Neider spike and tip gave Law the win.

Weston’s 25-17 match-tying win in game two was marked by the emergence of Maestri and Kathryn Joyce (5 kills). Law had 14 errors as the Trojans took a 21-13 lead.

Law’s Katie McNellis took over serve after a winning side out by Eden van Waveren, and the locals fought off three set points before Weston took a 2-1 lead in games.

The third set was a tour de force by both squads.

Long rallies with exceptional will displayed by decided most points.

Law led 11-10 after the first rotation, and Ellison made it 19-17 with an ace and an Eighmy dig that led to a Neider block.

Weston setter Kelly Rosemann then served her team in front with five points.

A Neider spike was good for a side out, but Maestri ended any possible drama with a well-placed kill for the 25-20 win.

Law looked to force a fifth set, but Weston libero Grace Donnelly (16 digs) made extending the match difficult.