BOSTON -- Jimmy Butler's belief in himself and his team is so strong that it is palpable within the Miami Heat's locker room.

After the superstar swingman dominated yet another postseason game -- scoring 35 points while racking up seven assists, six steals and five rebounds in Wednesday night's 123-116 win over the Boston Celtics in Game 1 of the Eastern Conference finals -- he acknowledged that he always believed this kind of run was possible for the eighth-seeded Heat, despite all the obstacles that have appeared in their way throughout the season.

"Damn right I did," Butler said. "Damn right we did. And the best part about it is we still don't care what none of y'all think, honestly speaking. We don't care if you pick us to win. We never have. We never will. We know the group of guys we have in this locker room. We know that Coach [Erik Spoelstra] puts so much confidence and belief in each and every one of us. Coach Pat [Riley] as well.

"So our circle is small, but the circle got so much love for one another. We pump constant confidence into everybody. We go out there and we hoop and we play basketball the right way, knowing that we've always got a chance."

The Heat continue to play their best basketball in the midst of a dream run through the playoffs that only they believed was possible. After squeaking out a win over the Chicago Bulls in the final Eastern Conference play-in game last month, the Heat knocked off the No. 1-seeded Milwaukee Bucks in five games and the No. 5-seeded New York Knicks in six. Now they have a 1-0 lead over the Celtics -- the team that beat them last year to advance to the NBA Finals.

The Heat, who have won Game 1 in each of their first three series during the 2023 postseason, are thriving in an underdog role -- a feeling underscored by their torrid play over the past month after an up-and-down regular season.

"I would say that everybody counted us out from the beginning was kind of what builds that chip," Heat big man Bam Adebayo said. "But also the adversity that we've been through the whole season, the ups and downs, the games we should have won but didn't win. Going to the locker room and trying to figure it out, rewrite whatever we did wrong, and going through that put us in this position.

"Now I feel like we are, like you said, one of the best teams in the league, because adversity built this. We all looked each other in the face and said, this is the second play-in game, this is our last run. This is it. From there, man, I just felt like everybody just bought into that will. I feel like we've just been willing wins."

Nobody is willing more wins in the league right now than Butler. After the Heat fell down by nine at halftime Wednesday, Butler helped engineer a third-quarter rally during which Miami outscored Boston 46-25, shooting 17-for-26 from the field.

"You can't quantify it," Spoelstra said of the belief Butler is bringing to the rest of the Heat's roster right now. "There's no analytic to it. Just the feeling of stability in the locker room. Even when you're down nine in the first half ... there's just a settling effect that is impossible to quantify.

"Like, all right, we are in striking distance. Let's just settle into our game, and Jimmy will make a bunch of plays, Bam will make a bunch of plays and everybody will be all right and everybody will just fit into their roles. But that's what the great players do."

Heat guard Gabe Vincent spoke for many in the locker room while describing what it's like to play with Butler right now.

"When Jimmy's playing like that, we feel like we can play with anybody, beat anybody," he said. "We got a couple guys in this locker room like that, but Jimmy's one of a kind."

The scary part for the rest of the league is that Butler brushed off the notion that this is the highest level his game has been at through the years.

"I don't think so," Butler said. "I really feel as though with anything in life, if you get the opportunity and you have the belief that my teammates, my coaches, Coach Pat, ownership have in me to kind of lead the charge, along with Bam right now, anything is possible.

"I'm playing at an incredible level because they are allowing me to do so. They are not putting a limit on my game. They are trusting me with the ball, on the defensive end. I think that's what any basketball player wants. That's what anybody wants out of life is just to be wanted, be appreciated and just let you go out there and rock."

Butler's teammates and coaches appreciate him because they know how much better he is making the group every night.

"It's fun," Heat guard Kyle Lowry said. "He's one of the best players in the world for a reason. It's just a joy to watch it. For a guy that wants it so bad and works so hard at his craft, it's important to enjoy his success. He gives us all the confidence to be successful and be aggressive and be assertive. That's what makes him special, that it's not all about him. He's about our group and our team and everyone else."