Knicks forward Mikal Bridges grabs the rebound against the Boston...

Knicks forward Mikal Bridges grabs the rebound against the Boston Celtics in the third quarter during Game 4 of the Eastern Conference Semifinals at Madison Square Garden on Monday. Credit: Newsday/J. Conrad Williams Jr.

BOSTON — The Knicks entered the postseason with a game plan that only a few would admit to but some in the locker room acknowledged: Hang close until the final minutes and then watch as the magic begins.

The magic? Jalen Brunson showing time and time again why he is referred to as “Captain Clutch” just as much as he is his given name.

But along the way, something unexpected happened: It became contagious. What once was just Brunson bailing them out suddenly has become a rotating cast of heroes, although Brunson still is the centerpiece around which it all revolves.

And as the Knicks head to TD Garden for Game 5 on Wednesday night with a 3-1 lead over the defending champion Celtics in the best-of-seven series, it’s no longer that simple to stop the Knicks.

They no longer are a one-man band.

With Celtics star Jayson Tatum suffering a ruptured Achilles on Monday and having surgery to repair it Tuesday morning, the Knicks have emerged as the favorites to win the Eastern Conference.

As he sat next to Brunson on the podium after Monday’s win, Mikal Bridges was asked if he too has the “clutch gene.”

“It’s the will to win,” Bridges said. “That’s pretty much it. Just having the fight to win, doing whatever it takes. I think last year, for a while, I was leading the league in fourth-quarter points for a little bit.”

He faded off as he said that, nodding toward Brunson, acknowledging who is the clear-cut leader in the final quarter most nights.

And while Brunson again is doing the sort of things that no player had ever done — he has scored 102 points in the fourth quarter in the first 10 games of the postseason, two more than the previous record-holder, Kobe Bryant — Bridges has scored 54 points in the fourth, with a 68% true shooting percentage.

On Monday, when the Celtics desperately tried to converge all of their defensive forces on Brunson, Bridges emerged with a series of crucial buckets, beating the shot clock as he arced one shot after another over the outstretched arms of Boston defenders.

It actually was Bridges who led the Knicks in scoring in the fourth quarter, shooting 5-for-6 for 10 points, although Brunson had 26 of his 39 in the second half.

That has become nearly as normal for Bridges as it is for Brunson. After a season in which the criticism of Bridges might have been second only to the scrutiny of the front office that dealt away five first-round picks to acquire him, he has managed to ease the worries of the fan base — and the front office — as he repeatedly delivered in the most important times on both ends of the floor.

In Game 1 of the series, it was Bridges who executed a steal that should echo in Knicks history, watching the eyes of Jaylen Brown as the inbounds pass soared toward the Celtics star and reaching in and ripping it away before Brown could get off a potential tying shot in overtime.

Game 2 ended nearly the same way. Bridges sneaked off Brown to help on Tatum, leaping in the final seconds to take the ball away from him and secure another victory in Boston.

“I’ve seen him since 2015,” Brunson said of Bridges, who won an NCAA championship with him at Villanova. “I’ve seen the way his work ethic has grown each year and I’ve seen everything he does, how psychotic he is with his work. It all pays off. I have full trust in him no matter what the situation is. That’s me and him, we don’t take things personal, we talk. Sometimes it’s good, sometimes it’s a little ugly, but we want to win. It’s been like that since the day I met him.”

“He’s been doing it all series,” Josh Hart said. “Huge steal Game 1. Fourth quarter and a block Game 2. This game was nothing different. Got us huge buckets in the fourth, huge stops. I’m so proud of him as a teammate, as a friend, going through all the adversity that he’s gone through this season. He’s never complained. He always comes to work happy, smiling. He deserves his credit and his flowers.”

More important than what he deserves is what he’s providing — another option for Brunson and the Knicks in the most important moments of the season.

“I think just getting better throughout the year,” Bridges said. “Obviously, JB, Josh, OG [Anunoby], guys have been here, but kind of like a new team a little bit with me and [Karl-Anthony Towns] coming in and Cam [Payne]. Just a little different, so we kind of had to figure out how to play together, the system and everything. It took some time.

“[The Celtics] have been together for a while. Regular season for them is just clockwork. They all know how to play off each other. Just took some time. The postseason, you get to know each other even more, how to play off each other. Just takes some time. I know everybody wants success early on. But we just kept getting better, all of us.”

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