SACO — Kristen Murray does a lot for Scarborough’s chemistry. In fact, she can make it downright explosive.

Murray scored four goals, including three in the third period, to lead Scarborough to a 6-1 victory over Cheverus in a Western Class A girls’ hockey semifinal Monday at MHG Ice Centre.

The top-seeded Red Storm (17-1-1) notched their first playoff victory to reach the regional final on Wednesday at Portland Ice Arena. They will host No. 2 York.

“This was massive,” Scarborough Coach Caitlin Cashman said. “It’s that mental game, ‘we lost in the first round the last three years, why wouldn’t it happen now?’

No. 5 Cheverus, which advanced with a 7-4 quarterfinal win over Biddeford, finished 6-13-1.

“We’ve come a long way,” Cheverus Coach Amy McNally said. “We scrimmaged Scarborough in preseason, and the difference in our play since then is night and day. I was happy with our effort and our focus tonight.”

Alyssa Hulst added a goal and four assists for Scarborough, and Sarah Martens had a goal and an assist.

But it was Murray’s turn to shine, playing in just her third game after missing seven weeks and eight games with a broken collarbone.

When Murray was hurt in a 2-2 tie against Greely on Dec. 22, Cashman said, “our lines got all mixed up, and we had to find our chemistry all over again. She’s a tremendously skilled player and other players were trying really hard to fill her skates.”

With Murray back in the lineup, Cashman said, offensive balance is restored, giving the Red Storm two strong lines.

That was evident from the start. Scarborough outshot Cheverus 12-5 in the period, but freshman Taylor Courtois (37 saves) let in only Murray’s power-play goal at 1:33.

“It’s always a race to see who gets the first goal,” Murray said. “We got out there and took charge.”

Courtois, who wears No. 15 and is listed as a forward, stepped into the goal at midseason and on Monday performed admirably under mounting pressure.

“It’s a tough position to put a freshman in,” McNally said. “But Taylor has embraced it.”

Not that Scarborough wasn’t dealing with pressure of its own.

“Losing the past three years in the first round was devastating,” Murray said. “We didn’t want that to happen again, so we came out with a lot of fire.”

Katie Roy countered 23 seconds after Murray’s goal to tie the game 1-1 in the first period.

Roy, one of two seniors on a young Cheverus team, was relentless.

“In the playoffs, anything can happen,” she said. “Compared to our other games against them (both 10-1 losses), we really stepped up.”

Hulst scored unassisted to give Scarborough a 2-1 lead after two periods.

“The second period, we picked it up,” said Scarborough goalie Devan Kane (12 saves). “And the third period was just like, ‘Pow!’

In the third, Scarborough held the Stags to one shot on goal while peppering Courtois with 16.

Murray showed her skill at finishing, scoring on a breakaway (2:09) from the slot (2:30) and capping a two-on-none with Hulst (9:42). Martens made it 6-1 with 2:18 to play and the Red Storm’s jinx was lifted.

“We knew in the back of our heads,” Kane said, “that the only way curses are broken is if you stop believing in them.”

True. And a potent offense helps ease doubts as well.