BIDDEFORD — It makes sense that Cape Elizabeth/Waynflete/South Portland scored its winning goal with two players sliding on their bellies, poking at the puck with their sticks.

After all, that was part of the plan all along.

A prone Kathryn Clark scored on the power play with 1:33 left to send the fifth seed to a 3-2 victory over No. 4 Biddeford in a Western Maine girls’ hockey quarterfinal Wednesday at Biddeford Arena.

Cape Elizabeth/Waynflete/South Portland (8-10-1) advances to the regional semifinals for the second straight year. It plays top-seeded Falmouth (14-4) on Friday at Family Ice Arena in Falmouth.

Clark called the winning goal “pure hustle. The last thing I saw was me and (Hannah Bosworth) diving, actually putting our bodies in the net. That shows what kind of team we are.”

The play was similar to the opening goal early in the first period with Bosworth scoring on a scramble in front of Biddeford goalie Rebekah Guay (23 saves).

“Guay’s a great goalie,” Bosworth said. “Coach (Bob Mills) told us to get bodies in front of her, screen her and get the puck in from the point. She’ll save the first shot but the second one’s up for grabs. It was a scrappy goal. They all were.”

Allison Mills made it 2-0 about 2:30 later, knocking in the rebound of Eliza Connolly’s shot from the blue line.

Cape Elizabeth/Waynflete/South Portland controlled play at the start, preventing Biddeford from getting its first shot on goal until 10:34 of the period. Defenders Kate Ginder and Connolly picked off clearing passes and sent the puck back in, where Clark and Bosworth combined for a number of gut-wrenching give-and-go plays. When Biddeford defenders Suzette Lamoureaux and Cassidy Petit weren’t blocking shots or riding attackers wide, Guay stood tall.

Biddeford’s effort paid off in the closing minutes of the period, as forward Abbie Paquette beat goalie Abby Joy (18 saves) with the first of her two goals at 13:24.

Cape Elizabeth/Waynflete/South Portland kept the pressure on Guay in the second, holding a 17-7 edge in shots and a 10-3 lead in shots on goal.

Biddeford made a game of it in the third as Rivard, Jessica Laverriere and Ailaina Keely put on pressure.

Clark finally gave Cape Elizabeth/Waynflete/South Portland some breathing room with a third goal. Ginder started the play with a long shot that found Guay’s pad.

Bosworth got a stick on the rebound, but Guay again got a pad on the puck. As a crowd collapsed on goal, the puck slipped along the goal line. Clark knocked it in.

“Kathryn brings a very consistent hardworking mentality to the team, and that inspires the rest of the players,” Mills said. “She’s won the state championship in soccer, so she knows what it takes to win.”

Moments after Clark made it 3-1, Paquette struck again to make it 3-2 with 1:13 to play.

“This was a good reminder that if you want to win a hockey game, you have to play all three periods,” Biddeford Coach Ashley Potvin said. “We got off to a slow start and tried to climb out of a 2-0 deficit, and that’s always tough to do. ”

Now it’s on to Falmouth, who swept the regular-season series with 3-2 and 4-0 wins.

“They’re an extremely skilled team and we need to be on our ‘A’ game to compete with them,” Clark said. “I think we can do it.”