"We don't really use 'underdog,'" Butler said Saturday, according to ESPN's Nick Friedell. "We may say that we have a chip on our shoulder, but I don't think that we're the underdog. I think that we're a really good team. We play together. Everybody knows their role. We just compete."
Butler added: "I think we're supposed to be here. That's how we think of it. To me, to us, that's all that matters. We're not underdogs. We're competitors."
The Heat entered the postseason as the No. 5 seed and swept the fourth-seeded Indiana Pacers in the first round. They then eliminated the Milwaukee Bucks, the presumed Eastern Conference favorites, in five games.
Miami also defeated the third-seeded Celtics 112-106 without Butler in the teams' only meeting inside the Disney World bubble. While the Heat lost the regular-season series 2-1, Butler says he and his teammates are confident that they're superior to their opponents.
"We all think that we're the better team," he said. "We all think that we're supposed to be here. And that's the way that I think. ... I love the way that our guys think like that as well, because I think confidence and your mental (approach) is the majority of this thing.
"We always talk about beating the bubble, I think we've done a great job of doing that thus far. So, going into these games, it's about us. We're in control of our destiny right now."
Game 1 of the Eastern Conference finals is scheduled for Tuesday.