BOSTON — The Boston Celtics trailed for the first 40 minutes of Game 2 on Wednesday night against the Brooklyn Nets in what was largely a sluggish offensive affair from Boston’s stars over the first three quarters.

The Nets had upped their intensity and physicality in the matchup and it was leading to tougher finishing opportunities for Jayson Tatum and Jaylen Brown. The Celtics had chipped away at a 17-point lead in the second half, getting it down into single digits but the Nets expanded it once again at the start of the fourth quarter to seven. With Boston staring heading back to Brooklyn in a 1-1 series with a potential boost looming for the Nets in Ben Simmons, the pressure was on for Coach Ime Udoka to push the right buttons and get the Celtics’ comeback to the finish line.

At that point, Udoka went with a unique lineup choice in a spot Boston’s closing five were usually ready in the opening minutes of the fourth quarter. Grant Williams was an obvious choice to get a chance over Daniel Theis at power forward given how hot of a shooting night he was having. However, the fifth and final spot on the floor was a tougher call.

The obvious choices were Marcus Smart or Derrick White based on Udoka’s history. Those guys were veterans that Udoka has trusted all year long in big spots. However, their lack of reliable 3-point shooting makes them potential weak spots in Boston’s offense when it comes to maximize spacing.

Smart had struggled with his 3-point shot all night (1 of 6) and White had gone just 1 of 5 from deep in this series. Knowing that, Udoka went with a more spacing-minded approach. He turned to his top bench shooter Payton Pritchard at the start of the fourth quarter for his usual minutes but ended up sticking with him for far beyond that after he hit a clutch jumper early in the quarter to pull Boston back within five points.

The Pritchard/Brown/Tatum/G. Williams/Horford lineup had played just six minutes together across three games all season long for Boston. Yet, in one of the biggest moments of Celtics’ season to date, Udoka turned to the unit to take down the NBA’s biggest stars.

The rookie coach’s instincts worked perfectly. In five minutes together, that five-man unit jumpstarted a 21-4 run to put the game away for Boston. Pritchard not only helped with his shot making inside the arc and timely rebounding but his presence on the floor as the perimeter threat helped to create easier opportunities for Brown and Tatum who combined for 17 fourth-quarter points.

“The spacing was different,” Udoka said after the win. “We like, obviously, our big lineups and didn’t feel like we were hurting them on the offensive glass and had some struggles defensively with the bigs, especially on Dragic tonight, so decided to go small and we’re obviously confident in Derrick and Payton and those guys, and Payton had a hot hand, had it going, but they guard him differently.

“The spacing, him being able to handle and be a shot maker as well as setting screens, so that worked well for us, we went with it and then obviously brought him back in, kind of offense-defense subbing with him and Theis. And our versatility showed tonight and was welcome.”

By the time, Udoka brought back Marcus Smart into the game with four minutes remaining, the Celtics were comfortably ahead by five, allowing the team to rely on their defense to carry them to the finish line.

It takes a lot of guts for any head coach, especially a rookie one to make that kind of a chess move in the fourth quarter of a playoff game rather than stick with reliable veteran weapons. However, Udoka has earned the faith of this group and his feel for personnel has continued to improve amid the team’s second half turnaround. That has earned him a vote of confidence from his top players.

“We all trust each other,” Tatum said. “We trust the coaching staff, they trust us and you just understand it’s a long game.”

“Ime showed his poise,” Jaylen Brown said. “He didn’t panic. In past years, that might’ve been the situation, but Ime didn’t panic. He just stayed with our game plan and made some minor adjustments. We played aggressive and we settled in a little bit, and we made some big plays, our role players made some big plays. Payton came off, was great. Grant was great as well, D-White, Theis – chipped in as a team and we got the win.”

The former Nets assistant is earning plenty of praise from his ex-players as well as Boston’s defense on Kyrie Irving and Kevin Durant limited the impact of the star duo throughout Boston’s Game 2 win.

“Ime knows us really well,” Irving said. “You know, he coached on our staff last year, so I think he has some keys in the treasure chest that he’s telling those guys.”

The end result is Boston being up 2-0 in a series they could have easily been facing a 0-2 deficit based on the numbers. Between the lineup tweaks and the decision not to call timeout at the end of Game 1, Udoka’s feel for the game is standing out well under the postseason lights.

ROBERT WILLIAMS will be on the Celtics’ bench as they travel to face the Nets, and his return from meniscus surgery appears to be close. Udoka said Thursday they want Williams to travel so he can be with the team but also experience the playoff atmosphere on the road.

Williams hasn’t played since March 27 when he tore his meniscus in his left knee, which initially looked like a huge blow to Boston’s postseason hopes. It’s been roughly three weeks since his surgery, though, and the Celtics said he should be back within 4 to 6 weeks. Williams is still right on track to make his return, which should set him up to return for a potential second-round series.

“He’s progressing well,” Udoka said. “He’s had no setbacks and that benchmark of what we said, the 4-6 weeks, is looking good. So we’re happy with his progress.”

Williams has yet to practice, but he has been working on the court and been around the team. Udoka said he’s doing other work on the side considering he doesn’t need to be at walkthroughs where they talk game plan.

BEN SIMMONS plans to make his season debut in Game 4 vs. Boston on Monday as long as rehab remains on course, sources told The Athletic.

Recently, Nets Coach Steve Nash said it was up to Simmons to give the green light. Simmons is rehabbing from a herniated disk in his back, and it’ll be up to him whether he plays in the first-round playoff series against the Boston Celtics, Nash said.

Simmons, who was traded to the Nets at the NBA trade deadline, was sent to Brooklyn with a kick in the pants by Sixers center Joel Embiid: “It’s unfortunate winning was not the biggest factor,” Embiid said of Simmons, his former Philadelphia 76ers teammate. “It’s unfortunate that for him having his own team and, I guess, being a star was more his priorities.”

KYRIE IRVING threw in the towel early during his last postseason series as a member of the Boston Celtics in 2019. It’s too early to say whether he will be doing so again with the Nets after falling into a 0-2 hole on Wednesday night at the TD Garden. However, the Nets’ point guard at the least sounded jealous of the foundation his former team had built without him.

“I’m not surprised at all,” Irving said of Boston’s success under Udoka. “I just think the timing is right. Their window is now for these young guys that are on this team that have matured. They’ve been through series together, they’ve been through seasons together, they’ve been through battles together.”

Irving battled through his worst performance of the postseason in Game 2, mustering just 10 points on 4-of-13 shooting from the field.

The Nets repeatedly showed a lack of cohesion in big moments for the second straight game after a season full of turmoil and trades.

The Nets will have a chance to get back into the first-round series back in Brooklyn on Saturday night at the Barclays Center. However, Irving is sure making it sound like the Celtics are the battle tested squad despite having a lot of the same talent that Brooklyn rolled over just one year ago in the first round.

“Our identity is what it is,” Irving said. “I just believe that, even me coming out tonight, and I only shot 13 times, I felt like we were in great position coming out of halftime just as a team. It’s no time for me to look at my individual stats and what I need to do. I want us to continue with that effort. I believe we can do it. We’ve just got to show it. This late in the season, even though I brought up team cohesion, it is what it is. We really have to turn the page and learn through our experiences right now.

“We’re going against a team together for what, the last four, five years. So they don’t have to worry about that. And I don’t want us to worry about it in this series and make excuses on why things are not going right for us. It’s just time to strap up the boots and get the ammo ready.”