LeBron James had 32 points and and Chris Bosh added 25 points - nearly matching his output from the first three games of the series combined - as the Heat topped the Indiana Pacers 102-90 in Game 4 for a 3-1 lead.
They are now just one win from yet another Eastern Conference title.
We try to get better every single day, every single game.
Dwyane Wade added 15 points and Miami never trailed, leading by 23 at one point.
"We try to get better every single day, every single game,'' James said.
"When you do that and go out and play the type of game that you are capable of playing, you can be satisfied with the results. And that's what we've built over the years.''
Only the Celtics and Lakers franchises have been to the NBA Finals in four straight seasons. The Heat now have three chances to join that club, starting with Game 5 at Indiana.
Paul George scored 23 points and David West added 20 points and 12 rebounds for the Pacers, who got 15 points from George Hill.
But Lance Stephenson was held to nine and 7-foot-2 centre Roy Hibbert was scoreless in 22 minutes for Indiana.
Miami have won the last three games in the series, and going back to the point in Game 3 when the Heat trailed by 15, they have outscored the Pacers by 39 points in a span of about 6.5 quarters.
The Pacers won two elimination games in the first round against Atlanta, and need to win three more if their yearlong plan of topping Miami is going to become reality.
Miami strong favourites
The odds are obviously stacked against them. When holding a 3-1 lead, Miami are 8-0 in Game 5s over the past four postseasons.
It was the 74th playoff game where James had at least 25 points, five rebounds and five assists, passing Michael Jordan for the most in NBA history.
In the other conference final series, San Antonio take a 2-1 lead to their next match with Oklahoma City.