The Maine Celtics overcame shooting woes to reach the NBA G League Finals. There was no surviving them when they returned with the championship on the line.

Maine’s historic season came to an end one victory from a G League championship Monday in front of a sellout crowd of 2,417 at the Portland Expo as the Oklahoma City Blue won Game 3, 117-100 on the strength of a 27-4 second-quarter run to win the best-of-three Finals and complete the rally after dropping Game 1 last week.

Maine finished the season, the first in which it reached the NBA developmental league’s championship series.

JD Davison scored 22 points to lead Maine, while Joe Wieskamp and Drew Peterson scored 13.

“It’s super frustrating, obviously,” Peterson said. “We thought we had a really good chance to win this thing going up 1-0. Give them credit, they made adjustments, they played really well.”

Ousmane Dieng scored 25 points to lead the Blue and was named Finals MVP, Jahmi’us Ramsey added 18 and  Lindy Waters III scored 15. Oklahoma City won 15 of its last 17 games.

“We knew what we wanted, and we executed and played hard,” Dieng said. “We started 2-9. … It’s been crazy. I’m really happy.”

A slow start, leading to a 29-22 first-quarter deficit, hindered Maine’s championship chances, but the Celtics responded with a strong second quarter and pulled even at 36 following an artful Davison layup with 6:06 to go.

And then the cold shooting that led to Maine scoring only 61 points through three quarters of the Eastern Conference final, and that had plagued it during a Game 2 loss in Oklahoma City, returned and devastated the Celtics’ title hopes. Maine made only one of its last 10 shots of the half, including an 0-for-5 mark from 3-point range, and turned the ball over three times.

“We just didn’t have enough tonight offensively,” Celtics Coach Blaine Mueller said. “They did a really good job, defensively, on us. Their physicality across the board, changing up defenses (was good).

“(And) another tough shooting night for us. In a best-of-three series, when you’ve got two nights like that, it’s obviously pretty hard to win a game, it’s pretty hard to win a series.”

While the Celtics’ shooting touch disappeared, the Blue found theirs after watching the lead slip away. Oklahoma City went back in front to stay on a 3-pointer by Waters – a two-way player for the Oklahoma City Thunder who missed Game 1, but scored 27 in Game 2.

It was the start of a deluge. Oklahoma City went 8 for 14 from the field after Maine pulled even at 36, including 4 for 7 from beyond the 3-point line, turning a tie game into a 63-40 halftime runaway in front of the stunned Expo crowd. Waters, who had two points before the run, scored 11 to lead the charge.

The Celtics couldn’t stop the Blue surge – even when they seemingly had. With Oklahoma City up 46-40, Ramsey missed a free throw, only for the Celtics to lose a grip on the rebound. The ball went to the Blue’s Olivier Sarr, who found Dieng for a quick-release 3-pointer and a 49-40 lead with 2:58 left.

“It was just a barrage of 3s that I thought, for the most part, were really well contested,” Mueller said. “The bigger issue was, the few times they missed, they got it and either got fouled or put it back in. And instead of a 9-0 run, it’s a 19-0 run, and all of a sudden the game’s kind of out of hand.”

Oklahoma City started the third quarter with a 7-0 run, pushing the lead to 30 at 70-40, but Maine restored a measure of drama and brought the crowd back into the game with a 12-2 run, making 5 of 6 shots from the field. The Celtics cut the lead to 74-58 on a Kylor Kelley free throw, but four points from Ramsey and then a 3-pointer from Dieng resumed the blowout.

Maine finished 40 for 94 (42.6%) from the field, and 11 of 39 (28.2%) from the 3-point line. In between Games 2 and 3, Davison, Peterson, Jordan Walsh and Neemias Queta played in the Boston Celtics’ games Friday and Sunday, but Mueller said their playing four games in five days had no effect on Monday’s performance.

“None. They shot the (expletive) out of it in Boston. They played great,” he said. “If you can’t find it for the deciding game in the Finals, I don’t really have a whole lot for you. I didn’t really think it was legs. Maybe a little bit of anxiety, maybe a little bit of pressing. Guys really, really, really wanting to make shots.”