SACO — Stop us if this sounds familiar: A South Portland High boys’ team struggles through an up-and-down regular season, then turns it up in the playoffs.

It happened in basketball when the Red Riots went from under .500 all the way to the state final. Wednesday it was the boys’ lacrosse team – like basketball featuring 6-foot-5 Jack Fiorini – that played its best game of the season to knock off fourth-seeded Thornton Academy 11-8 in a Class A South quarterfinal.

Fifth-seeded South Portland (8-5) won its fifth straight game and will be at top-ranked Scarborough on Saturday. It was the third straight season South Portland beat Thornton in the playoffs, the last two coming in regional finals at South Portland.

Fiorini scored three goals on hard left-handed shots that helped him earn a preferred walk-on spot next fall at Syracuse University.

Two came early as South Portland jumped on the Trojans for a 3-0 lead. His third pushed the lead back to three goals at 10-7 with 8:38 remaining.

But five other Red Riots figured in the scoring, and freshmen attack Cooper Mehlhorn (3 goals, 3 assists), Mitchell Adams (2 goals) and David Fiorini (2 assists) were pivotal. Jake Angell, a junior first-year starter, added two goals and an assist.

“We’ve become a complete team,” said South Portland Coach Tom Fiorini, Jack and David’s father. “Everyone looks at us and thinks we’re one-dimensional with Jack, but he’s done a great job all season of teaching the younger players how to play South Portland lacrosse and it’s showing. Everyone is working together. The ball is being shared and now when we make the passes to the younger players, they’re more confident and putting the ball in the cage.”

Mehlhorn’s second goal late in the first half pushed South Portland’s lead to 6-2 and came a split-second before Mehlhorn was planted to the turf by sizable Thornton defender Isaac Patry.

“We just felt coming in that we were going to get hit around, we were going to get pushed, but we just had to take the hits,” Mehlhorn said, “and it paid off.”

Thornton (8-5) rallied in the third quarter when Thomas Pike, Justin Masteller, John Giroux and C.J. Labreck scored in the first 5:25 to make it 6-6.

“We were able to score a bunch of goals off fast breaks and then when you do that, your own guys get tired,” Thornton Coach Ryan Hersey said.

South Portland settled itself with goals by Adams and Angell to regain an 8-7 lead entering the fourth quarter.