WINDHAM — It was a gamble, and it paid off for the Portland High boys’ soccer team.

The fourth-seeded Bulldogs moved junior Pedro Bunga to offense for the first time this season, and he scored the winning goal as Portland knocked off No. 1 Windham, 2-1, in a Class A South semifinal on Saturday.

Bunga scored with 6:41 left to send Portland to the regional final at 4 p.m. Tuesday at Massabesic High against No. 3 Scarborough, which beat second-seeded Falmouth, 2-1.

“All summer long, Pedro was playing up top,” said longtime Portland Coach Rocco Frenzilli. “Then, during preseason, we started playing him in the back and he was incredible. Now, with Walter (Hettenbach) stepping up (at left back), we decided this week to give Pedro a run up top. It made all the difference in the world.”

Bunga’s goal came off a feed from Paulo Joao.

“That was all coach’s work right there,” said Bunga, through his interpreter, Mateta Antonio. “I was happy when I got moved to offense. I was waiting for this moment.”

Joao gave the Bulldogs a 1-0 lead five minutes into the game when he finished a feed from Baptista Muanda, beating Eagles goalkeeper Lukas Hammond (six saves).

Windham (13-2-1) responded with 5:51 left in the first half when Luke Cunniffe headed home a corner kick by Jack Henry.

Early in the second half, Sam Rogers fired a shot past Portland goalkeeper Marco Cifuentes Robles (two saves), but it hit off the underside of the crossbar and stayed out.

Bunga later hit the crossbar before ringing a shot off the left post. He wasn’t denied on his final opportunity, however, as he sent Portland to its second straight regional final. The Bulldogs lost to Deering last year.

“Hopefully, we’ll generate more than we did last year,” said Frenzilli. “Scarborough and Falmouth will try to stop us from generating. It’s going to be a great chess match and I’m just happy we’re going to be there.”

Windham, which featured an abundance of seniors in key positions, was knocked out by Portland on its home field as the top seed for the second year in a row.

“I feel badly for the seniors,” said Windham Coach Jeff Neal. They’ve done so much and accomplished so much the past four years. There’s a lot of emotion and heavy hearts right now, but there’s nothing I can say.

“I’m very proud of how the guys have carried themselves respectfully. They dug in and showed sportsmanship all the way through.”