WATERTOWN — After falling to Shrewsbury in the Div. 1 girls hockey final last season, St. Mary’s coach Frank Pagliuca had nearly an entirely new roster to work with this season.

Fortunately for the Spartans, they have Bella Freitas and Gianna Tringale on their side.

Freitas scored both St. Mary’s (21-3-1) goals on Thursday, including the game winner on a power play with 3:24 left in regulation, while Tringale stopped 25 of 26 Colonials shots to give the Spartans a 2-1 win and a spot in Sunday’s state semifinals.

“This basically was a brand new group this season and I’m extremely proud of how they’ve fought all season,” Pagliuca said.

Tringale was on her game all night as the Colonials (13-5-5) easily could have had a two- or three-goal lead through two periods. Her remarkable save on Natalie MacCausland’s shot at a yawning net early in the second period was followed moments later by Freitas converting off a Shrewsbury turnover in its own end.

The defending champions weren’t quite ready to surrender their crown as MacCausland sniped a wrist shot inside the left post just 101 seconds into the third to tie the game.

It was still tied at one with just under five minutes left when Shrewsbury took a penalty. The Spartans showed great patience and puck movement as they worked the puck finally down to Freitas, who was able to lift a backhander over Risa Montoya’s glove for the game-winner.

“Gianna played tremendous. She let that first one in and didn’t let it bother her,” Pagliuca said. “And Bella was just tremendous. They were physical with her all game and she stayed with it.”