BOSTON (AP) — The latest Eastern Conference finals pairing between the Heat and Celtics will be a matchup that ultimately turns on the play of stars like Jimmy Butler and Jayson Tatum.

But Miami’s 123-116 Game 1 victory also showed how the tactical battle between rookie coach Joe Mazzulla and veteran counterpart Erik Spoelstra will also play a big factor.

The Celtics dominated the first two quarters on Wednesday night before being outscored 46-25 in the third period – the most points they’ve allowed in any playoff quarter over the past 25 years. It put Boston into a 103-91 hole it never overcame.

The game-changing onslaught also included a 13-1 run by the Heat to help tie the game in which Mazzulla made the decision not to call a timeout, something that has become a recurring theme for him this season because of his preference to let the Celtics play through rough patches.

“I don’t think it’s a challenge in the postseason, I think it’s human nature,” Mazzulla said Thursday when asked about his team’s tendencies to surrender leads this season. “So how are you able to get out of that and win that and just understanding your environment, understanding your opponent? It’s hard to do, but what we’re trying to do is really hard.”

After back-to-back series in which Boston has fallen into 0-1 holes, it’s cast the spotlight back on the 34-year-old, who was thrust into his dream job in the preseason and is now trying to find new ways to motivate a team with championship expectations.

Miami’s Spoelstra knows well what it’s like to be in that position.

The 52-year-old Spoelstra grew up in the Heat organization, rising from video coordinator to assistant to head coach at 38, and then successfully balanced the pressure of turning a team led by All-Stars LeBron James, Dwyane Wade and Chris Bosh into back-to-back NBA champions.

Spoelstra acknowledged that he doubted himself initially, recalling how he was heckled in his first game in New York by Knicks fans who asked, “if I was up past my bedtime.”

“I was beating myself up quite a bit,” Spoelstra said of his first season.

Likewise, Mazzulla has made no secret that he has learned something with every game he has coached.

That includes the playoffs. During the last series, Mazzulla listened to pleas from the Celtics’ veteran leaders to reinsert Robert Williams III into the starting lineup. He also apologized to the team for not calling a timeout prior to its final possession in Game 4 overtime loss to Philadelphia.

“He trusts us. At the end of the day, Joe trusts us,” Celtics guard Malcolm Brogdon said.

That humility is why Spoelstra respects what Mazzulla has done to this point, going through the challenges of an NBA season.

“I think just going through the fire, going through the experiences,” Spoelstra said. “Every situation is different. So, I don’t know what it’s like in this locker room, this building. But I have a lot of respect for Joe. We have a lot of mutual friends. We saw each other a lot in the (Florida) bubble. … We always seemed to be bumping into each other all the time.”

And now they’ve bumped into each other three of the past four postseasons.

While his team is an underdog this time around, as one of the league’s longest tenured head coaches, Spoelstra is proving yet again how good he is at getting the best out of his players.

Despite a slow start in Game 1, Spoelstra let Butler set the tone throughout, including trusting his star to guard Tatum, despite Butler dealing with an ankle issue that slowed him the previous round against New York.

It increased the amount of energy Tatum had to exert and contributed to him not taking a shot in the fourth quarter, despite a 30-point scoring night.

It’s part of what has become the Heat’s culture under Spoelstra, teams led by stars but depending on the collective for ultimate success.

He said Butler epitomizes that.

“On the ball, off the ball, all that stuff,” Spoelstra said. “Settled us offensively. That’s a big part of us not turning the ball over, is just having a place where you can throw the ball and get a bit more settled.”

That said, Spoelstra expects Boston to respond in Game 2 on Friday. Not just because of the players they have on the court, but because of the guy patrolling the sideline.

Spoelstra said he can tell Mazzulla has already grown as a coach.

“You go through it, the experience,” Spoelstra said. “That’s the best thing. The most valuable thing. What he’s done this year is not easy. You definitely have to respect that.”