The Lakers were outscored in every quarter of the game as they got their first look at the revamped Heat, who handed the defending champions a 96-80 loss
Kobe Bryant, Pau Gasol and Lamar Odom combined for 48 points.
Miami's big three -- LeBron James, Chris Bosh and Dwyane Wade -- collectively scored 69 points. James finished with a triple double.
Although both teams called it just another game rather than a potential NBA finals preview, it clearly meant something to James, who outplayed Bryant again in his second straight Christmas win at Staples Center.
"It's a long season and we're not even half way through it," said Lakers guard Shannon Brown. "You've got to get better every game. It's a marathon."
The Lakers have lost two straight at home after winning five in a row on the road, following up Tuesday's collapse against Milwaukee.
Bryant, who picked up his third technical foul in two games, was visibly displeased with his teammates throughout the second half.
The Lakers are 21-9 on the season, including a 10-4 record at home.
After a shaky start, the retooled Heat move on to 23-9. This was Miami's 14th win in 15 games.
The Associated Press contributed to this report.