JD Davison weaves his way through Capital City Go-Go players during the Maine Celtics' 115-95 win in the first round of the NBA G League Eastern Conference playoffs on Tuesday in Portland. Davison had 38 points, 12 assists and four rebounds. Brianna Soukup/Portland Press Herald

Miles Norris was watching shot after shot go in. Drew Peterson was swishing shots in transition. JD Davison pulled up for a long 3-point try seconds before the end of the first quarter and that, too, went in.

The 3s were falling like layups, and it made for a festive Tuesday night at the Portland Expo for the Maine Celtics and their fans.

Davison scored 38 points to go with 12 assists, Jordan Schakel and Norris added 16 points apiece, and Maine turned a blistering start from beyond the arc into a runaway 115-95 win over the Capital City Go-Go in the first round of the NBA G League playoffs.

Maine, the Eastern Conference’s third seed, never trailed en route to earning a semifinal matchup Thursday at Westchester, which got a first-round bye as the No. 2 seed. Capital City was the No. 6 seed.

“We had a few days to periodize how we were going to go over all our coverages and all of the adjustments,” Celtics coach Tyler Lashbrook said. “I thought our guys just had a really high level of focus during those days, and a real attentiveness. I thought they executed at a really high level.”

In its first playoff test since reaching the G League Finals last seasons, Maine showed the same torrid shooting that characterized parts of that run. The Celtics were 14 for 23 from the field in the first quarter and a scalding 9 for 11 from 3-point range as they raced out to a 40-20 lead. Maine made 12 of its first 16 shots from deep and finished with 20 3s — breaking the team playoff record of 16 — on 44 tries.

“It’s hard to stop Maine whenever they’re shooting like that,” said guard Jordan Walsh, who joined the Celtics on assignment from Boston and scored 11 points. “(We) came out in the first half on fire, I was like ‘Oh my goodness.’ I was on the bench watching, just enjoying the show.

“They had no answers. What are you going to do? You can’t compete with us if we’re making 3s at that clip.”

It was a turnaround from Maine’s shooting performance in its last game, a 122-113 defeat against Westchester in which the Celtics shot 17 for 46 (37%) from 3.

Drew Peterson takes a 3-pointer against Capital City. Peterson scored 14 points and made 3 of 9 3-point shots. Maine made 20 of 44 from 3-point range. Brianna Soukup/Portland Press Herald

“I told them to throw that game out the window, and save it for the next game,” Davison said. “(My teammates) came out and hit shots. I tip my hat for them, (we’ve) got to keep it going.”

The initial spark came from Norris, who knocked down 4 of 5 3-point attempts in the first nine minutes and helped Maine jump out to a 25-13 lead.

“It was good to see him aggressive, it was good to see him take those opportunities,” Lashbrook said. “I thought he impacted the game on both ends.”

Maine’s shooting touch cooled in the second quarter, but its defense held Capital City to misses on its first eight shots and 5-for-21 shooting for the quarter. The Go-Go started hoisting up 3-pointers in an effort to climb back into the game but made only 1 of 10 attempts before going into halftime down 59-35.

Maine’s lead peaked at 36 points, and the Celtics were up by at least 20 for the entire second half, which became the Davison show. The 22-year-old guard totaled 16 points in the first half, then poured in 22 after halftime. He set a career high with seven 3-pointers, and hit them in his first nine attempts.

JD Davison gets foul while taking shot against Capital City. Davison made the basket. Brianna Soukup/Portland Press Herald

“If you ask my opinion, he’s MVP of the league,” said center James Banks III, who had six rebounds and four blocks. “What you saw tonight is what he’s capable of every night.”

Davison provided highlight after highlight, whether it was a 3-pointer from well behind the line, an acrobatic layup through traffic or everything in between. He didn’t slow down as the game got out of hand; with 7:33 to go in the third quarter and Maine up 75-46, he raced up court to block what looked like a breakaway layup for JT Thor, then vigorously signaled for a review when he was called for a foul. He was correct, and the call was reversed.

“I try to make plays on both ends of the court,” he said. “A play like that can get the team going.”

Maine didn’t have to worry about getting going Tuesday.

“It was good, but honestly, it’s right to Westchester for us,” Lashbrook said. “It’s going to be a quick turnaround, and with our guys, I think that’s where their minds are at.”