NEW YORK — Kristaps Porzingis always enjoys coming back to Madison Square Garden, even if the fans there aren’t welcoming to him. He was once the Knicks’ promising young star, drafted to be the face of their future before he was suddenly traded in 2019. That makes him an enemy whenever he returns.

Porzingis knows this. He embraces it. On Wednesday night, it fueled him.

With 2:03 remaining in a tight season opener, Knicks fans got mad at him. Porzingis, after corralling a rebound, was fouled and inadvertently hit Isaiah Hartenstein with an elbow, sending him to the floor. The Garden erupted. “(Expletive) Porzingis!” chants filled the arena.

“I did not hear,” Porzingis said with a wry smile afterward.

Of course, he did. It didn’t bother him.

“For me it was fun,” Porzingis said. “I was just enjoying all of that and using it as motivation to make some big plays at the end. It was actually really, really fun tonight to play and be in that environment.”

It was only fitting that Porzingis was the one who willed the Celtics to their season-opening victory. Facing his former team, in the arena he called his first NBA home, Porzingis showcased so many of the ways he can be the difference-maker that propels Boston to a championship this season.

With the extra spacing he provides, he killed the Knicks with his shooting. He was a terror defensively, making fans forget about Robert Williams, as an elite rim protector as he finished with four blocks and several more stops. In crunch time, he showed he might be the piece that the Celtics had been missing in those late, tight moments as he scored nine consecutive points to close the victory.

When Jayson Tatum faced a double team and found Porzingis open for the ultimately decisive 3-pointer with 1:29 to go, Tatum stretched out both of his arms in celebration. Porzingis took the load off his shoulders.

“He just makes us that much more dynamic obviously with his size, ability to shoot, make plays off the dribble,” Tatum said. “When they double me late, make the right play, find an open man. Obviously he can shoot from wherever. I mean, he’s really good. He’s really, really good. We’re lucky to have him.”

The significance of coming through in crunch time wasn’t lost on Porzingis.

“It’s important, I think,” Porzingis said. “It’s important to show what my mindset is in tight games like this and probably showing them that I’ll be there. I’ll be there and do what I can on both ends. I think today was a good step for us to build that trust.”

Defensively, the Celtics flashed their potential on Wednesday. Derrick White and Jrue Holiday created some havoc as they forced some turnovers to get the Celtics in transition. Holiday helped shut down the bigger Julius Randle, who went just 5-for-22. The Celtics’ effort and togetherness on that end showed in crunch time as they consistently limited the Knicks to one shot and held them to just five points over the final four minutes.

Porzingis’ defense almost stood out more than his offense. He was the biggest reason why the Knicks struggled to have success inside, as they were held to 18-for-56 on two-point field goals.

Porzingis gave credit to the coaching staff for putting him in the right situations and positions on defense, an area he seems energized to show what he can do.

“KP is hungry and excited to be here,” Tatum said. “And knows how important he is to this team and what we need him to bring each and every night. It’s a sense of pride that we, everybody has to have on defense, right? We got some All-NBA defensive guys on this team, some guys that are capable of making that team. And essentially, you don’t want to be like the slouch out there, right? And KP is definitely holding his own and everybody individually wants to hold their own defense so we can be better as a unit. And that’s just a pride thing and effort.”

Other takeaways:

– Jaylen Brown struggled. He finished with 11 points and made some bad decisions throughout the night, including a costly sequence in the fourth when he committed two turnovers and a foul on a 3-pointer as the Knicks surged ahead. But he earned some credit for some of the Celtics’ late-game execution.

“It was just one game,” Tatum said. “We know how special he is. Everybody’s going to have not great shooting nights but he still impacted the game in other ways. He got some key rebounds and loose balls at the end to give us some more possessions. I’m not going to shoot the ball great some nights, KP’s not, but it’s all about how you impact the game in other ways. So JB’s going to be fine. He’s probably going to have a great game on Friday.”

– While Holiday looked great – as usual – defensively, he’s clearly still trying to get comfortable with the offense as he continues to build chemistry and learn tendencies with some new teammates after being traded less than a month ago.

“I think he’s still learning,” C’s coach Joe Mazzulla said. “Especially when you’re out there with four guys that can dribble-drive, you gotta just find your opportunities to play and find your opportunities to space and find your opportunities to screen. We just gotta simplify it for him.”

– A big, necessary area of clean-up for the Celtics: They gave up 17 offensive rebounds to the Knicks, resulting in 20 second-chance points.

– Tatum has dealt with his fair share of injuries over the last few seasons, including his wrist and the ankle injury he suffered in Game 7 of the Eastern Conference Finals last season. He said before the season opener that his body feels good after a full summer off, and he looked fresh in the win over the Knicks as he finished with 34 points and 11 rebounds. He did commit four turnovers, though, including one that was nearly costly in the final minute as the C’s were trying to hold on.

“I had too many turnovers,” Tatum said. “It was the first game of the season, cut me some slack.”

– The Celtics reported zero injuries and are fully healthy for Friday’s home opener against the Heat.