The defining moment in Portland’s baseball season came May 26 with a come-from-behind victory against Cheverus that built a foundation for what’s happened since.

Four straight wins to close the regular season, a victory in the SMAA playoffs and now this – another come-from-behind win Thursday night against Deering in the Western Class A quarterfinals.

The Bulldogs (13-4) used a big fifth inning to beat Cheverus, and it was the fifth inning again that beat the upset-minded Rams.

Top-ranked Portland scored four runs in the fifth to overcome a 3-0 deficit and beat ninth-seeded Deering 4-3 before a large crowd at Hadlock Field.

Portland will play fourth-seeded Falmouth (11-6) at 1 p.m. Saturday at Hadlock Field in the semifinals.

Deering (11-7) had the Bulldogs on the ropes until the bottom of the fifth. The bottom of Portland’s order got things started and then the Rams’ defense fell apart, making four errors. What was a 3-0 lead soon became a 4-3 deficit.

“We’ve had several come-from-behind wins this season. Maybe 50 percent of our wins have been that way,” said winning pitcher Ryan Ruhlin, who relieved in the fifth. “We feel out the pitcher for the first couple of innings and then we start to hit.

“We have a great batting order. In the back of our minds we knew we were capable of winning the game. We weren’t down mentally at all when we fell behind early.”

Deering left-hander Colby Dame pitched well enough to win.

“We had some mental lapses and we got a little tight at the plate after we lost the lead,” said Deering Coach Josh Stowell.

After Dame struck out the first batter in the fifth, Zach Fortin, the No. 8 batter who had two hits, singled to right-center. Dom DiMillo, who had only four plate appearances coming into the game, singled to right. Jake Knop drove home Fortin with a single to left.

Pinch-runner Marcus Cross Robertson scored on a passed ball, and a squeeze bunt scored Knop from third to tie it. John Williams reached on an error, and when Ruhlin’s single to center was mishandled, Williams went to third, then continued home when the throw from the outfield got past third base.

Ruhlin relieved Charles Barnard with two outs in the fifth and retired seven straight to close it out.

“Ryan has been our team MVP,” said Portland Coach Mike Rutherford. “Counting the league playoffs we are 14-5. Ryan has six pitching wins and four saves, so he’s contributed to 10 of our 14 wins. And he leads our team in RBI.”

Deering scored a run in the second and two in the third. James Sinclair singled sharply up the middle with two outs in the second and scored from first on an outfield error.

In the third, Ian Westphal led off with a single. Kevin Goldberg was hit by a pitch and Nick Bevilacqua bunted the runners along. Dom Bernard was intentionally walked to load the bases. Pat Viola was hit by a pitch to bring in a run and the Rams made it 3-0 on a fielder’s choice.

“I’m proud of the guys. Our goal at the start was to go .500 and make the playoffs. We did a lot more. The players stayed tough throughout the season,” said Stowell.