"All I care about is the win," James said. "I didn't even know my stats. I just knew that we were playing efficient offensively besides the turnovers. We want to try to keep that going."
Dwyane Wade scored 16, Chris Bosh added 15 and Chris Andersen finished with 10 on 4 for 4 shooting for the Heat, who opened their title defense by holding Milwaukee to 42 percent shooting and outrebounding the Bucks 46-31.
Brandon Jennings scored 26 points and Monta Ellis added 22 for the Bucks, who have not won the opening game of a playoff series since May 2001.
Game 2 is Tuesday in Miami.
"We've got nothing to lose," Jennings said. "Nobody should be scared or anything. Let's just hoop."
James had taken only 11 shots in a playoff game twice before, and his postseason per-game average entering Sunday was just under 21 tries. But with the way he controlled the game Sunday, he didn't exactly need to shoot.
That's probably not the best of signs for the Bucks.
"Obviously, incredibly efficient," Bucks coach Jim Boylan said. "When you have a game like that, what can you do?"
Milwaukee came into the series with Jennings predicting his team would oust the reigning champions in six games.
They'll have to win four of five now for that to happen.
And with James playing like this, the odds would seem particularly slim. He had 10 rebounds and eight assists both game-highs.