BOSTON — If we have learned anything from three Eastern Conference finals meetings between Miami and Boston over the last four years, it is that the Heat never quit, but with 18 seconds left in a two-possession game on their second night of a new NBA season, they had little other choice against the retooled Celtics.

Derrick White, the leading scorer in a lineup boasting four All-Stars, lured Tyler Herro and Kyle Lowry 30 feet from the basket. White found Jrue Holiday, who drew Bam Adebayo and Kevin Love to the free-throw line. The attention paid to Boston's fourth and fifth options left an All-NBA wing on his own, so Holiday swung the ball to a wide-open Jaylen Brown, whose 3-pointer was the dagger in a 119-111 victory at TD Garden.

This is not the team that failed in its attempt to erase a 3-0 conference finals deficit against Miami. Boston added Holiday and Kristaps Porzingis. Nor are the Heat the same. They lost two playoff starters and spent the summer waiting on a Damian Lillard trade that never came, and they reckoned with that on Friday night.

"They're different," said longtime Heat head coach Erik Spoelstra, who was weighing his words carefully and will spend the season plotting revenge for this loss. "We've been at this with them for four years since the bubble. It really has been a privilege to be able to face them in the playoffs so many times. But both teams have changed. That's the way this league goes, that's the way life goes. So they're different."

Different is one way to put it. Stacked is another. All five Celtics starters scored well into double figures, led by White's 28 points. He and Brown had 26 of Boston's 32 fourth-quarter points. White's late chase-down block of Miami's Jimmy Butler also punctuated the effort to hold the Heat to 4-for-19 shooting in the frame.

"We still didn't play great fourth-quarter basketball," figured second-year Celtics coach Joe Mazzulla in full growth mindset. "For Game 2 of what we're trying to do, it's a good start, but we've got a long way to go."

And a long way they have come, if this is how they will execute down the stretch of close games. Boston has yet to face adversity this season, its kryptonite in pursuit of a title in recent years, but if the first two games are any indication, the presence of Holiday and Porzingis pops the pressure that has plagued them.

"We played with a sense of poise," said Mazzulla, turning a phrase he could not when last we saw his team. "We attacked the right matchups. We got to our spots. It was a good balance of shooting open 3s, getting to the free-throw line and posting up the mismatches. And defensively we made some timely possessions."

Starting with White and Holiday, Boston's All-Defensive backcourt, who combined for four blocks ... again.

"I'm trying to be the best player I can be, trying to be one of the best players in the world on both ends, and it inspires you when guys like Jrue and D-White are getting chase-down blocks," said Jayson Tatum, whose 22 points were third-best on the Celtics behind Brown's 27. "You don't want to be the weak link out there."

That's a back-to-back All-NBA first-team forward trying not to be the weak link. It is early, obviously, but the Celtics are acting like a team whose biggest problem so far is figuring which of many mismatches to attack.

"If we want to have a chance to maximize our talent and our team, each guy has to be at their best, and so that is where the sacrifice comes in," said Mazzulla, also more poised than in his chaotic rookie season. "We're not going to be able to replicate this every night, but what we saw was each individual guy being their best and playing together. So, the the more we replicate that, the more we can maximize who we are."

Against the New York Knicks on Wednesday, Tatum and Porzingis combined for 64 points. The Heat were more pointed in stopping Porzingis' pick-and-pops, which freed White and Brown for 55 points on Friday.

"It's going to be like that each night," said Brown. "We've got to all be comfortable. That's going to be a challenge. Teams are going to guard us different ways, give us different looks. We've got a lot of talent, so we let the game decide. Tonight, D-White took advantage of his matchups. We've made some some good reads. ... Each and every game, we've just got to be ready and be aggressive, but the game will decide what's going to happen. We've just got to continue to find each other in rhythm, and we'll be all right."

It helps to have Holiday, the unselfish final piece to Milwaukee's 2021 championship puzzle. The Bucks dealt him in favor of Lillard, so he made his way to Boston via the Portland Trail Blazers for training camp.

"He does so many little things that doesn't show up on the stat sheet, but it just helps us win games," said White. "Having a guy on our team who probably doesn't see the ball for 10 minutes, won't complain, just does what he needs to do and makes a big shot down the stretch — both sides of the ball he's big-time."

Ideally, this ripple effect extends to a bench that has left much to be desired through two games. After scoring 12 points against New York, Boston's reserves combined for only eight points opposite the Heat.

But here's the thing: They don't have to do all that much when the starters are averaging more than 100 points per game. They can hyper-focus on their roles, and for Oshae Brissett on Friday that was banging the offensive glass, which he did twice to jumpstart the first-quarter scoring. Boston out-rebounded Miami by a wide margin, including 16 offensive rebounds that the Celtics turned into 23 second-chance points.

"We've got real stars on this team, so me coming in, just being myself, not trying to do too much, not trying to prove I could do anything else — even though, you know, they all know I can," joked Brissett, flashing a smile that informs you he knows where he stands on this team, before adding, "We've got a lot of guys who are athletic. We're really tall. Even Jrue out there, he's very active, and D-White. You go down the line of all the guys that can be on the floor, we know that we're good at doing that specifically, so it really doesn't matter who's guarding us or who we're playing, we're going to try to play the same way every single time."

This is the mark of a team that knows at its best it can dictate the terms of its title pursuit. The Celtics were humbled by a 2022 Finals loss to the Golden State Warriors and mortified by last season's loss to the Heat in the conference finals. They should know by now not to get too far ahead of themselves, and they might.

"Last year is last year," said Brown, four days removed from his 27th birthday. "I think we've grown. We've got a lot of players who can make poised decisions down the line, and we've just got to continue to keep that up. It's only two games in, and we've still got a lot of work to do, so I'm looking forward to doing that."

That work for the unbeaten Celtics continues Monday against the winless Washington Wizards.