‘Every time I shoot, I think it’s going in’

Like just about every Knicks player outside of Evan Fournier, RJ Barrett got off to a poor start on Thursday night against the Boston Celtics, scoring four points in the first half on just 1-of-8 shooting.

He made just three of his first 14 shots overall, but he hit the one that mattered most: an off-balance buzzer-beating three over Jayson Tatum to give the Knicks a 108-105 win, sending The Garden crowd into a frenzy.

“It was definitely a tougher shot, you know Jayson’s so tall,” Barrett said after the game. “Every time I shoot, I think it’s going in.”

Barrett’s shot banked in off the glass, and replay showed he clearly got it off just in time. By the time the ball had hit nylon, Barrett was on the floor, and while he didn’t see it happen, the crowd and his teammates’ reaction was all he needed to know what he just did.

“I honestly didn’t even really see it because I fell,” Barrett said with a laugh. “I didn’t even see it go in, but just from everybody else’s reaction, I could tell, so that was cool.”

“That was the play and then whoever was open got the ball,” he added later. “I just so happened to be open.”

Barrett’s shot capped off what was a wild game. After playing uninspired basketball in the first half, in which the Knicks found themselves trailing by as many as 25 points, they stormed back in the second half, led by Fournier’s career-best 41 points.

The atmosphere in The Garden was electric, as the crowd could feel the Knicks clawing their way back. By the time the final buzzer sounded, the Knicks and Celtics had finished another classic game, just like their 138-134 double overtime game to start the season.

“Man, this was like a playoff game. It’s crazy,” said Barrett. “It was like the first game of the season, too. Whenever we play them it’s a battle, so it’s been a lot of fun.

“We knew they were going to come out aggressive, especially after losing that game the night before. But they played…