Jayson Tatum’s triple-double helped the top seeds to lead throughout against last season’s losing finalists.
The Heat entered the play-offs as the number eight seeds after beating the Chicago Bulls in a play-in eliminator.
But without injured star player Jimmy Butler, the Heat found the Celtics too strong in the opener to the best-of-seven series.
Tatum scored 23 points, had 10 rebounds and provided 10 assists – and was one of six players to score double figures for Boston, but warned his side they “can’t relax” against the team which eliminated them from the play-offs last year.
“They’re not going to give up, they’re not going to lay down,” he said.
There are 16 teams in the first round of the play-offs, playing best-of-seven series in a knockout format. The eight winners go through to the next round.
James Harden scored 28 points for the Los Angeles Clippers as they beat the Dallas Mavericks 109-97 in the first game of their series.
The home side led 56-30 at half-time and despite a fight back led by Luka Doncic and Kyrie Irving, with 33 and 31 points respectively, the Mavericks were left with too much to do.
The Indiana Pacers visit the Milwaukee Bucks later, while the New Orleans Pelicans travel to face the Oklahoma City Thunder.
Were you a believer, as we headed into the Playoffs, that it’s #DifferentHere this season in Boston? If not, maybe Game 1 between the Celtics and the Heat did a bit of convincing for you.
Boston came out Sunday afternoon and destroyed the Heat while making a statement to them and to the league that this version of the Celtics is much different than last year’s version of the Celtics. As many will remember, Miami marched into TD Garden during last year’s Eastern Conference Finals and stole Games 1, 2 and 7 en route to a shocking series upset.
