There was no semblance of their two NBA Finals matchups against each other.
James scored 24 points with some early baskets on nifty passes from Dwyane Wade, and the Heat rolled to a 110-95 victory Thursday night, a game in which Miami led by 36 points before James and Wade sat out the entire fourth quarter.
"I'm just playing within the game," said Wade, who had 19 points and six assists. "My job is to do a little bit of everything right now."
Including getting the ball to James, who has scored at least 20 points in all 23 games, the longest streak to start an NBA season since Karl Malone's 24 in a row opening the 1989-90 season.
"I'm just very comfortable and confident in my ability," James said. "I put a lot of work into my game. It's always good when you put in the work and implement that into a game situation."
Nowitzki, the Mavs' 11-time All-Star, hasn't played this season though he practiced for the first time this week since arthroscopic right knee surgery Oct. 19. Dallas is now without starting point guard Derek Fisher (right knee) and post players Elton Brand (right groin) and Brandan Wright (right ankle).
The Heat never trailed after James drove for a short floater 3 minutes into the game. They had their first double-digit lead, 22-11, when James made a 3-pointer with 4 1/2 minutes left in the first quarter.
"We don't want to give a team too much confidence at home. We understand this team was short-handed," Wade said. "We wanted to come out here on the road and make a statement."
Chris Bosh added 17 points as the Heat played only their second road game since Nov. 17. They return home to play Utah on Saturday before an NBA Finals rematch against Oklahoma City on Christmas Day.
LeBron James' first 3 came in between two impressive passes from Wade, who didn't yet have James or Dallas native Bosh as teammates when the Heat clinched their first NBA title in the same building in June 2006.
Dallas is much changed team since winning the 2011 NBA title over the Heat, in the star trio's first season together. Miami is now defending a championship this season.
"Much better team than we were. We know each other," James said. "We can close our eyes and where we're going to be offensively and defensively."
Mavericks coach Rick Carlisle wholeheartedly agrees with that assessment, and is dealing with the opposite side of that since Nowitzki and Shawn Marion are the only current Dallas players who actually played in the NBA Finals only two seasons ago.
"They're so much better now since they've been together and there's a lot to be said about being together," Carlisle said. "Right now one of our struggles, we have a group that hasn't been together too much. ... And it's been challenging."
Bosh rebounded a missed 3-pointer by the Mavericks and got the ball to Wade, who had a perfect alley-oop pass to James, who caught the ball in midair near the rim and slammed it through with both hands.
After another missed 3 by Dallas later in the first quarter, Wade grabbed the rebound under the basket and then threw a football-like pass the length of the court to James. Even with Darren Collison and Vince Carter fronting him, James leaped and reached over to grab the ball, then finished with a layup to make it 27-13.
Dallas pulled to 36-33 after Dominique Jones had consecutive assists to rookies, a 3-pointer by Crowder and a reverse layup by Bernard James.
But Miami then responded with a 16-4 run.
Miami stretched the lead to 91-55, its largest of the season, when Shane Battier made a 3-pointer with 1:21 left in the third quarter.
Nowtizki practiced for the first time Wednesday, and had an individual workout Thursday. It's still unclear when he will make his season debut, but got a huge cheer when he was shown on the video screen during a timeout.
Collison, who lost the job as the starting point guard when the Mavericks signed Fisher on Nov. 29, was back in the starting lineup and had 11 points.
Fisher was hurt in the first quarter of a win over Philadelphia on Tuesday night. He will skip a two-game trip for games at Memphis on Friday night and San Antonio on Sunday. The team said there is no timetable for the 38-year-old Fisher's return and that he would be re-evaluated next week.
Mavs guard O.J. Mayo made only three of 14 shots for eight points before facing his former team on Friday night in Memphis. ... The Heat's largest lead this season before Thursday night had been against Washington last week, when they led by 35 points in the fourth quarter. ... Heisman Trophy winner Johnny Manziel, the freshman quarterback from Texas A&M, was sitting courtside early in the second half. He watched Philadelphia at Houston on Wednesday night. ... When play resumed after a timeout with about 7 minutes left, many fans were watching a fight in the stands instead of the game.
J.R. Smith made seven 3-pointers and the Cleveland Cavaliers drained an NBA-record 25 3s in a 123-98 runaway win over the Atlanta Hawks on Wednesday night in Game 2 of their second-round series.
The Cleveland Cavaliers set the record for 3-pointers made in an NBA game, playoff or regular season, sinking 25 to rout the Atlanta Hawks in Game 2.
Led by J.R. Smith's seven treys, the Cavaliers set an NBA record by draining 25 3-pointers in their 123-98 Game 2 win over Atlanta on Wednesday night.