SOUTH PORTLAND — A patient attack and persistent defense carried the South Portland boys’ lacrosse team to a second straight Western Class A championship Wednesday, as the Red Riots wore down Thornton Academy for a 12-4 victory at George E. Martin Memorial Field.

South Portland, the 2014 state champion, returns to the state final at 10 a.m. Saturday at Fitzpatrick Stadium. The Red Riots will play Eastern champion Brunswick.

Saturday’s championship game will be a rematch of last year, won by the Red Riots, 10-8.

So how did the Riots make it back to the state title game?

“It was all hard work, we’ve been at it for years,” said senior middie Chris Mitchell, who led the Riots with three goals and three assists. “It feels great.”

Possession decided this one.

“Ground balls and faceoffs,” South Portland Coach Tom Fiorini said. “We were very patient on offense. They run a really tight zone on ‘D,’ so patience is the key. Defensively, we wanted the midfield to get back and slow down their attack. We gave up I think two goals in transition, and that’s a big part of their game. We had to play smart lacrosse today and we did.”

And get back they did. Faced with Thornton’s lethal transition offense, which averaged nearly 14 goals per game this season, the Riots built big edges in ground balls (48-23) and faceoffs (15-4).

That, in turn, led to a considerable edge in possession, which accounted for South Portland’s advantage in shots (38-21) and shots on cage (30-12).

Senior attack Andrew Whipple bolstered the Riots’ attack with four goals and an assist. Senior attack Kam Andrews also had three goals, and draw specialist Lucas Michaud had two goals and two assists.

Thornton Academy was led by senior attack Zach Bryant, who scored twice. The Trojans also got goals from Thomas Pike and Gregory Ruff.

“There’s nothing to hang our heads about,” said Thornton Coach Ryan Hersey, whose teams have reached the regional final four times in the last six seasons. “Possession really was the difference. Our game plan defensively was to stay in close so we didn’t (get spread out). Once we did (get spread out) we were in trouble because they pass the ball so well. They don’t even have to get their heads up to pass; they just know who is where and where the ball is going.”

South Portland took a 2-0 lead six seconds apart as Michaud fired the rebound of a shot past Chris Camire (18 saves) with 9:06 left in the first quarter, and Whipple buried a pass from Michaud off the faceoff at 9:00. Bryant and Isaac Sinclair answered for Thornton and the teams ended the first quarter tied at 2.

Andrews scored from the high slot (7:50) and in close (4:36) to give the Riots a 4-2 lead at halftime.

South Portland outscored Thornton 4-1 in the third period and put the game away with a 4-1 burst in the fourth.

“It all starts with possession. GBs win games,” said South Portland senior goalie T-Moe Hellier (eight saves). “That’s been our motto since freshman year and we’ve been able to capitalize on it lately. And then (Michaud) came in and started winning faceoffs for us, and that’s always nice.”