The Knicks will look to bounce back quickly from the problems they suffered in Boston on Tuesday to open the season, and it will have to start defensively.

The Celtics raised the banner to commemorate their 2024 NBA title, then blasted the new-look Knicks, who have plans to challenge the Eastern Conference champions this season.

“That’s championship-level basketball. For us, it was a punch in the mouth and we have to respond,” guard Miles McBride said after the game. “It’s obviously a long year. You can’t overreact to one game, but I don’t think you can go into a year like that and set the tone.”

It’s hard to dispute that assessment after the Knicks flopped in their first game with the two new starters acquired in separate offseason trades, Mikal Bridge and Karl-Anthony Towns.

“I have a lot of confidence in our offense. We have to bring that defensive identity that is going to make us special,” Towns said. “Once we figure that out, we’ll take the next step and be the team we want to be.”

Bridges had no answers for his top defensive assignment, All-Star forward Jayson Tatum, who led the way with 37 points and made eight of the Celtics’ NBA-record-tying 29 3-pointers.

They shot as much as 60.4 percent from long range (29-for-48) at one point before missing their last 13 attempts from beyond the arc while trying to reach a new goal.

“Indecision. Second and third tries,” Tom Thibodeau said when asked what went wrong defensively. “When you play against a team like that, you have to scramble and fly around.

“One effort will not be enough. You have to make a second, third and fourth attempt.’

The Knicks will focus on improving that defensive effort in their home opener Friday night at the Garden against the Pacers, the team that eliminated them in the second round of the playoffs last spring.

All-Star guard Jalen Brunson said having two new starters was “the easy way out” because “we were still impressed.”

“They’ve been at it for a long time, and we’re a pretty new team, but that’s no excuse,” added Brunson, who scored 22 points but was minus-23 in 24:30 of playing time. “Personally, I have to be better. It starts with my approach and everything, and I just have to be better.

“We can say a lot. We can analyze everything. They made a lot of 3s. They probably made more than we took home. But we have to be better on both sides of the ball. I have to be better on both sides of the ball.”

The same goes for OG Anunoby, who was minus-21 with just four points on 1-for-7 shooting. And for Bridges and Towns, both of whom had ineffective two-way debuts.

Obviously, it will take some time for the revised starting lineup and rotation to come together following the departures of Julius Randle, Donte DiVincenzo and free agent Isaiah Hartenstein, as well as the absence of injured center Mitchell Robinson.

“We’ll look at what we did, what we needed to fix and get back to work,” Thibodeau said. “Every game reveals things to you. Sometimes you do things well, sometimes not as well as you need to. But understand why you lost or won and take the necessary steps to move forward.”