Jimmy Butler is confident the Miami Heat can turn things around after falling 3-2 behind to the Boston Celtics in the Eastern Conference Finals.

Miami must now win back-to-back games after slumping to a 93-80 loss on Wednesday, despite having taken a 42-37 half-time lead.

Boston can seal the series on home court on Friday, but Butler is determined to take it to a Game 7 decider on Sunday.

"Besides the fact that anything is possible, we know what we are capable of," he said.

"We know we can play some really good basketball, and we know that we are going to play some really good basketball.

"It's going to have to start in this next game up in Boston. But I just think that we know that we can win."

Butler left Game 3 early with a knee problem and has since been 7-of-32 from the field in consecutive losses.

However, he was in no mood to make excuses for his poor showing.

"It doesn't matter; if I'm out there, I've got to do better," he said. "I've got to find a way to help us win, and I haven't been doing that.

"I'm fine. My knee is okay. I've just got to do better. It's no excuse."

Team-mate Kyle Lowry struck a similarly defiant tone as he sought to issue a rallying call ahead of a crunch clash in Boston.

"We have to continue to just keep working," Lowry said.

"It's the first to four, so we have to go into a hostile environment, and it will be amped up, but I like what our team can do.

"I like the opportunity that we have, and we've got to go in there and fight."