Knicks guard Jalen Brunson (11) heads back to the bench...

Knicks guard Jalen Brunson (11) heads back to the bench during the second half of an NBA basketball game against the Boston Celtics, Tuesday, Oct. 22, 2024, in Boston.  Credit: AP/Charles Krupa

BOSTON — The Knicks retreated to the locker room 30 minutes before game time on opening night at TD Garden, finding a quiet spot to ignore the festivities while Boston celebrated last season’s championship.

It was their 18th championship banner being raised to the rafters, while the players and coaches for the Celtics came out one by one to wild applause to receive their rings.

Ignoring the celebration, the Knicks came out for the first test to see if their remade roster — much of it with the Celtics as a blueprint for it — was ready to challenge for their turn atop the NBA.

Let’s just say the first impression is that it may take a little time.

Whatever Boston did in cruising through 64 regular- season wins and just three losses in the postseason seemed like a warmup for what they put on display Tuesday night. The Celtics dominated the Knicks for a 132-109 win.

Celtics coach Joe Mazzulla, when he came to get his ring, stopped and went to the parquet floor, kissing it. Asked after the game what it tasted like, he said, “Blood.”

On Boston’s very first possession of the game Jayson Tatum lost Mikal Bridges around a screen and easily drained an open three-point field goal. And then Boston repeated that over and over until Tatum had piled up 37 points and the Celtics had built leads of as much as 35.

They converted an NBA record-tying 29 three-point field goals — even with Kristaps Porzingis watching from the bench in a suit. Only 13 consecutive misses down the stretch while fans chanted “One more three” kept the Celtics from setting the record for a team.

Opening night jitters are one thing and even if the Knicks wanted to claim that this was a measuring stick, putting together this group and thinking that in three weeks of training camp they’d match the cohesion of the defending champions seemed like a big ask.

“Yeah that’s the easy way out, but we still got our [butts] kicked,” Jalen Brunson said. “We’ve just got to come out and see what we can do to be better.

“Yeah they’ve been at it for a long time, and we’re a fairly new team, but that’s no excuse.”

The Celtics proved to be the machine that they were last season, but the Knicks showed that this is a work in progress. Brunson did what he does, finishing with 22 points on 9-for-14 shooting. Deuce McBride was 8-for-10 for 22 points off the bench.

Karl-Anthony Towns had a quiet 12 points and seven rebounds. Mikal Bridges recovered from a nightmarish first half in which he shot 0-for-5 — 0-for-4 from three — to finish with 16 points.

But the real problem was on the defensive end where the Knicks bore no resemblance to the team that they were last season. Bridges was unable to stay with Tatum, Towns was attacked repeatedly and the wing pairing of Bridges and OG Anunoby that was assembled to match the dangerous Boston duo of Tatum and Jaylen Brown was never a deterrent on this night.

“NBA needs to drug test all of them,” Josh Hart said. “I’ll tell you that right now. Because I ain’t never seen nothing like that before.

“You’ve got to give them credit. They’re already an explosive team and obviously there was an energy in the arena that was contagious. They played extremely well. We’ll look at it, we’ll learn from it, look at some of the defensive mishaps that we had that led to their shots, but it’s game one.”

“Indecision. Second and third effort,” Knicks coach Tom Thibodeau said. “When you play a team like that you got to scramble and you got to fly around. One effort is not going to be enough. You got to have a second and third and fourth effort.”

The only bright spot the Knicks could point to is that, in trailing by 35 points in this game, it doesn’t have to portend disaster. The last time these two teams met in April, the Knicks built up a lead of as many as 31 in a win — and a few months later the Celtics were celebrating a championship.

“I don’t really put too much into it,” Hart said. “They won last year, obviously. Porzingis isn’t there right now. And it’s a new season, so I don’t think it’s anything more than opening night.”

Notes & quotes: A league source indicated that the Knicks and Westchester native Matt Ryan, who shot 45.1% from three for New Orleans last season, are working through the details and he could be a veteran addition to the roster.

Westchester native Matt Ryan, who shot 45.1% from three for New Orleans last season, are working through the details and he could be a veteran addition to the roster.

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