STANDISH — Three playoff games, three hits.

That’s all the Falmouth pitching staff has allowed.

Left-hander Cam Guarino tossed his second one-hitter in six days to lead top-seeded Falmouth to a 4-2 victory over second-ranked South Portland in the Class A South baseball championship game Tuesday night at St. Joseph’s College.

Falmouth (19-0) will face defending state champion Bangor (18-1) at 1 p.m. Saturday at St. Joseph’s for the state title.

Falmouth actually fell behind Tuesday. South Portland (16-3) parlayed a catcher’s interference, two errors, a single by Ben Conti and an accidental hidden ball trick into a 2-1 lead in the top of the third.

Falmouth responded by scoring three unearned runs, aided by a two-out throwing error, to take the lead for good.

Guarino didn’t allow another baserunner. He retired the last 13 batters.

“He’s just an outstanding pitcher,” South Portland Coach Mike Owens said of Guarino. “We knew coming in that he was going to be all over the zone, and throw three pitches and compete. I thought we put some good swings on the ball. We just couldn’t get that timely hit or find a gap.”

As in previous playoff victories over No. 8 Deering (4-0) and No. 5 Portland (5-0), Falmouth jumped to a first-inning lead. Connor Aube doubled, Tyler Gee singled and Robbie Armitage made it 1-0 with a fielder’s-choice grounder.

The Red Riots ended Falmouth’s 14-inning postseason scoreless streak in the third.

Riley Hasson was awarded first base when his swing at an 0-2 pitch clipped the mitt of Falmouth catcher Garrett Aube before tipping the baseball. Sam Troiano reached on an error and Conti singled up the middle to load the bases.

Drew Abramson followed with a slow grounder to shortstop Robbie Armitage, whose throw to first skipped just before Abramson arrived in a headfirst slide. While first baseman Jesse Melchiskey frantically searched for the ball, Troiano followed Hasson across for a 2-1 lead.

“It was utter confusion,” Melchiskey said. “I had no idea where it was. It actually ended up under the baserunner. When he got up, he kicked it out and that’s when I saw it.”

In the bottom of the third, it was South Portland’s turn to stumble in the field. Pitcher Griffin Kelley appeared to escape from a two-on, none-out jam by inducing a shallow fly, a strikeout and a slow grounder to short, but Abramson’s wild throw allowed Colin Coyne to reach as Connor Aube scored the tying run from second.

Chris Camelio (three hits) and Melchiskey followed with sharply hit run-scoring singles to make it 4-2.

“We can hit all the way through the lineup,’ Melchiskey said. “That takes a lot of teams by surprise. We’ll see a lot of fastballs down in the order and we look to capitalize on that.”

Guarino took over from there, with defensive help from Connor Aube in center and Robbie Armitage at short.

“After that third inning, I just wanted to get everyone out,” Guarino said. “I was a little mad that they started getting some runs off me. I tried my best to outsmart them and keep them off balance.”