It was a night that was going to leave the Miami Heat at a loss, regardless of the outcome, with Jimmy Butler’s night done at halftime due to knee inflammation.

But that also is where the Heat held the line, riding the aggression of center Bam Adebayo to a harrowing 109-103 victory Saturday night over the Boston Celtics at TD Garden and a 2-1 lead in the best-of-seven Eastern Conference finals.

On the rare night when the Heat started whole, with point guard Kyle Lowry back from his hamstring strain and power forward back P.J. Tucker from a knee issue, the Heat soon had to find a way to finish in the absence of their scoring leader.

So Adebayo became their scoring leader, closing with 31 points and 10 rebounds, after scoring a combined 16 in the series’ first two games, including a key late jumper.

With Lowry providing stability in his return and Tucker aggression, the Heat rode a variety of complementary contributions on both ends, including a key late Max Strus 3-pointer, on the way to regaining homecourt advantage.

Strus added 16 points, with Lowry closing with 11 points and six assists, and Tucker 17 points and seven rebounds.

Jaylen Brown led the Celtics with 40 points.

The series continues with Monday’s 8:30 p.m. Game 4 at TD Garden.

Five Degrees of Heat from Saturday’s game:

1. Closing time: The Heat led 39-18 at the end of the opening period, their scoring high for any quarter this postseason, pushing that lead to 26 in the second period, before taking a 62-47 lead into the intermission.

The Celtics closed within nine in the third, but the Heat advantage again was 15 going into the fourth quarter, at 87-72.

And then, suddenly, a 20-4 Celtics run trimmed the Heat lead to 93-92 with 2:40 to play.

But that’s when Strus stepped up a 3-pointer with 2:16 to play to put the Heat up 96-92, with Adebayo following with a 17-foot jumper with 1:21 to play.

Further doubt ended when Lowry snuck in to steal a Celtics inbounds pass and feed Strus for a layup that made it 103-94 with 42.5 seconds remaining, allowing the Heat to withstand a late Brown 3-pointer.

2. Always something: The rare night when the Heat started whole took a decided turn to the concerning when Butler was unable to make it out for the start of the second half due to recurring knee inflammation.

That had Victor Oladipo, who did not play in the first half, with the starters at the open of the third period.

Butler’s night ended with eight points, three rebounds and two assists in 20 minutes.

Butler previously missed the Heat’s Game 5 closeout victory over the Atlanta Hawks in the first round due to inflammation in the right knee.

3. Message received: At the morning shootaround, Heat coach Erik Spoelstra said of Adebayo, “We want him more involved.”

Message received.

Adebayo opened 5 of 6 from the field, scoring his 10th point 5:37 into the game.

Adebayo’s 12th point moved him past Tim Hardaway for 10th on the all-time Heat playoff list and he was up to 16 points at halftime. He had 23 points going into the fourth.

4. Lowry back: Lowry was back after missing eight of the previous 10 games due to a strained left hamstring, re-establishing his leadership with the first unit.

Mindful of the ailment, he went into the locker-room tunnel during his time out of the game.

Lowry, 36, previously had attempted to return from the hamstring in the second round against the Philadelphia 76ers after a four-game absence, only to miss four more games.

Spoelstra stressed that the setback against the 76ers was not a setback in terms of Lowry’s rehab.

“He didn’t reinjure,” Spoelstra said. “I think that was important, so he still was able to heal. If he did reinjure it, I think he would have been out a lot longer. It’s just he still felt it, so we erred on the side of caution and taking more time.”

With Lowry back but on a minutes watch, Gabe Vincent, who had started in his place, was first off the Heat bench, splitting the 24 first-half minutes evenly with Lowry.

5. Tucker, too: Also back was Tucker, who bruised his left knee in Thursday night’s Game 2 loss to the degree that there were initial thoughts of requiring an MRI.

Tucker left Thursday night’s loss at FTX Arena after first injuring the knee in the first half and the aggravating it in the third quarter.

He then had eight points and four rebounds in Saturday night’s first half.

Spoelstra paused when asked what it would take to keep Tucker, 37, out.

“I don’t know,” he said. “I think all of us, you’re kind of on eggshells with him. You can’t ask him how he’s doing. I can’t ask a trainer, because if he sees me talking to a trainer, he barks at me and yells at me if I’m talking to the trainers. I’m allowed to talk to the trainers, that is part of my job.

“But he is a throwback by every definition of that.”

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Observations and other notes of interest from Saturday night’s 109-103 NBA playoff victory over the Boston Celtics:

– Heat coach Erik Spoelstra rarely shows his hand before a game.

– Any hand. Any game.

– Saturday morning was different.

– With Bam Adebayo averaging a meager eight points two games into this series, on an average of five shots, he knew more had to be done.

– And that Adebayo had to be doing more.

– “We want him more involved,” Spoelstra said before noon at TD Garden. “And I have to do a better job of that, of making sure that he’s involved, engaged, giving us some triggers.”

– Spoelstra paused, as if to make clear he wasn’t talking about handing the keys to Adebayo.,

– “It might not necessarily be what everybody thinks it may be,” he said. “But he’s a very important part of our offense and how we function.”

– So they treated him as such.

– And Adebayo treated himself as such.

– “I think we’ll be able to get him in places where he can be assertive in how he was all season,” Spoelstra said.

– That mission was accomplished in the opening minutes, Adebayo up to a series-high 10 points with 6:23 remaining in the opening period.

– Now all that is needed is for Adebayo to do it again.

– Because with Jimmy Butler’s right knee again inflamed, there might not be any other choice.

– Even with Kyle Lowry back.

– Even with Victor Oladipo available.

– The twists keep coming.

– But at least the Heat on Saturday night untangled Adebayo.

– With Lowry (hamstring) and P.J. Tucker (knee) available, the Heat got back to their primary starting lineup, one rounded out by Butler, Adebayo and Max Strus.

– With their starts, Butler and Lowry both tied Terry Porter for 79th on the all-time NBA playoff list, moving them past Moses Malone and Dennis Rodman for 80th.

– With Spoelstra mindful of Lowry’s minutes, previous starting point guard Gabe Vincent was the first reserve off the Heat bench.

– Dewayne Dedmon followed, and then Tyler Herro and Caleb Martin together.

– Then, briefly, Duncan Robinson.

– And eventually Oladipo out of necessity.

– Butler’s first point moved him past Rick Barry for 79th on the all-time NBA playoff list.

– Butler’s third point moved him past Cliff Hagan for 78th on the all-time NBA playoff list.

– Adebayo’s 12th point moved him past Tim Hardaway for 10th on the all-time Heat playoff list.

– Lowry’s first 3-pointer moved him past JJ Redick for 27th on the all-time NBA playoff list and tied him with Rasheed Wallace for 26th.

– Lowry’s first steal moved him past Tony Allen, Jamaal Wilkes and Terry Porter for 62nd on the all-time NBA playoff list.

– Strus’ second 3-pointer moved him past Damon Jones for 20th on the all-time Heat playoff list.

– Spoelstra went in stressing that he knew if his ailing players could play they would.

– “We have a locker room full of these kinds of guys,” he said. “There’s been so much narrative in this league about load management, guys resting, guys sitting out for better or worse. We don’t have guys wired like that.”

– Celtics coach Ime Udoka went in seeking a solid start in order to inspire the home crowd.

– “I’d say in general, our starts at times weren’t the best in the Milwaukee series, even Brooklyn to some extent early,” Udoka said pregame. “To get the crowd into it, you want to have good starts.”

– He added, “I don’t think we focus on home or road as much as some other teams maybe. We’ve been really good on the road at times, as you saw in the Milwaukee series. And so for us it’s neither here nor there.”

– Udoka pregame also discussed the emotional approach of guard Marcus Smart toward his Celtics teammates.

– “I’ve always said guys have been receptive to constructive criticism and they have the freedom to discuss, debate and talk back if they have something to say,” he said. “So an open line of communication from all of us I think has been beneficial. Feelings don’t get hurt.”

– He added, “Guys that have been together for a while can get on each other and respond in the proper way. And so Marcus is a guy that plays with his emotions on his sleeve, says what comes to mind at times. I don’t think guys are sensitive to the delivery. It’s more so what’s being said.”

– Spoelstra also addressed Smart’s fire, “You have to respect Marcus as a competitor more than anything.”

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