Lakers star Anthony Davis scored a game-high 34 points in his Finals debut, while LeBron James had 25 points, 13 rebounds and nine assists in Los Angeles' first game back in the championship series since 2010.
"I just try to go out there and be comfortable knowing that this is the moment I've waited for my entire career. And now I'm here," Davis said. "So maximize this opportunity because it doesn't come around too often."
Entering Wednesday night's matchup, James' teams had been a combined 1-8 in the opening game of the Finals -- with losses in each of the last seven openers. The three-time NBA champion and the Lakers reversed that trend with a smothering and physical defense that left the Heat with a handful of critical injuries.
Jimmy Butler battled through a twisted left ankle and scored a team-best 23 points for the Heat. Miami also lost starting point guard Goran Dragic in the first half to a left foot injury and had All-Star big man Bam Adebayo exit in the third quarter after he appeared to aggravate a left shoulder injury.
Heat rookie guard Kendrick Nunn entered the game for Dragic and scored 18 points in 20 minutes. Tyler Herro had 14 points and Jae Crowder -- tasked with guarding Davis for most of the night -- finished with 12. Adebayo was limited to eight points and four rebounds in 21 minutes before departing.
The Heat controlled the first six minutes of the contest and appeared ready to steal Game 1 of the series from the Lakers, who entered as the favorites to win the title. Miami scored on six straight possessions in what turned into a 13-0 run to grab a 23-10 lead midway through the first quarter.
But the Lakers started to settle in and began to connect from beyond the arc. Los Angeles went 9 for 11 on 3-pointers over the final 16 minutes of the first half and quickly turned a double-digit deficit into a 65-48 lead at the half.
The Lakers started the third quarter on an 18-3 run and the route was underway.
"We kind of picked it up on both ends of the floor," Davis said.
Kentavious Caldwell-Pope notched 13 points, Danny Green scored 11 and Alex Caruso ended up with 10 for the Lakers, who led by as much as 32 points in the contest. Los Angeles outrebounded Miami by a 54-36 margin and sank 15 3-pointers to take control of the game.
"We got so much more work to do," James said. "The job is not done and we're not satisfied with winning one game. It's that simple."
Game 2 of the best-of-seven series is Friday night.