STANDISH — Bailey Tremblay said Saturday that she and the Thornton Academy softball team could not afford to be intimidated against No. 1 Scarborough.

Tremblay took her advice and shut down the potent Red Storm in a three-hit, 2-1 win, outdueling Scarborough ace Alyssa Williamson in Tuesday’s Western Class A regional championship at St. Joseph’s College.

“We weren’t intimidated coming into it. We were very confident but not overconfident,” Tremblay said. “We knew that we could compete if we play our game. That’s what we did. We stuck together and came out with the win.”

Thornton (16-3), which has won 14 straight, makes its first state softball championship appearance at 4 p.m. Saturday against Skowhegan at St. Joseph’s.

Defending champion Scarborough (18-1) lost its fourth straight even-year Western final, having fallen to Biddeford in 2008 and South Portland in 2010 and 2012.

“We came in here relaxed and ready to go but props to TA, they definitely came in here ready to play,” said Williamson, who allowed six hits in a complete game. “It’s hard, coming in here and Bailey was just on and it’s hard to produce runs and get people on base so we can move them over when she’s doing so well.”

Down 1-0, Thornton scored its runs on an infield single by Maizee Lee (2 for 2). Tremblay scored from third after she’d reached by beating out an infield single.

Then Kaylee Burns ran into Scarborough third baseman Maggie Murphy as she tried to round third. According to Thornton Coach John Provost he saw the base ump make an immediate obstruction call and sent Burns on.

Scarborough second baseman Ashley Gleason threw Burns out with Megan Murrell blocking the plate but the call was overturned and Burns was credited with a run.

“As soon as I see his hand go up I’m waving Kaylee on the whole way,” Provost said. “She made the turn and there was no play (at third) and she ended up plowing into the third baseman. He made the right call and it was clearly obstruction.”

“We got beat by a team that played extremely good defense all day long,” Scarborough Coach Tom Griffin said. “Defense and pitching wins these types of games. It’s just disappointing the game was decided by an obstruction call. My argument was, whether she was obstructed or not, it was an easy out at the plate but (the umpire) didn’t see it that way.”

Scarborough scored its run in the first inning when Brittany Plowman drew the only walk off Tremblay, went to second on Williamson’s single to left and scored on a single up the middle by Murrell.

With runners still at first and second, Tremblay got Breanna Kent to ground to second base where Taylor Lux started a crisp 4-6-3 double play, with shortstop Brooke Cross’ strong throw to stretching Erin Brayden beat Kent by a full step.

“Our team just bought into the fact that defense wins championships and the turning point was when we turned that double play in the first inning,” Provost said. “That was a momentum changer.”

Tremblay retired 16 of the next 17 Scarborough batters before Kent lined a one-out single in the seventh.

Lux (six assists) handled the next two plays, getting a tough force out at second and then reacting quickly to Abbie Murrell’s grounder that tipped off Tremblay’s glove and threw out Murrell from her knees for the final out.