Chalmers' basket ended a run of six straight points and made it 79-60, and the Heat lead was 85-63 after three.
The Nets were trying to tie a franchise record with their 12th win of the month, and now will face a tough start to February when they host Chicago on Friday and the Lakers next Tuesday.
Brooklyn has been a different team since Carlesimo replaced Avery Johnson in late December. The Heat said they've noticed little change in the Nets' scheme but plenty in their effort, James essentially saying it was too bad Johnson had to take the fall for the Nets not wanting to play harder earlier.
The effort was there Wednesday. It wasn't nearly enough.
James loudly made his entrance, screaming "He here!" as he entered the locker room. The Nets made their pitch to him three summers ago in free agency, and haven't beaten him since he decided on Miami instead.
Miami hit seven of its first 10 shots, led 30-20 after one quarter, and was up by 12 with 7½ minutes left in the first half. But the Nets got much tougher defensively, getting some help when the Heat got sloppy and started turning it over and missing free throws, including three in a row by James and Wade. Blatche hit all five shots in the second, Lopez added six points, and the Nets came all the way back to even it at 49 when Williams made a jumper with 2.3 seconds remaining.
"We just knew we could play better," Wade said. "That's all we talked about in the locker room was 'Listen, we can't turn the ball over,' and to play that well to start the game off and to give the lead back and it's tied coming into halftime, that's not what we want to do. Our job, we want to get better on the road, not get worse, so I thought we took a step forward."
The Heat had just about all the highlights from there, a brief "Lets' go Heat!" chant even breaking out in the second half.
Notes: Though Nets owner Mikhail Prokhorov is in town from Russia for this game and Friday, Carlesimo said they had no discussions planned about his job status. "I don't feel the need to, or anything like that," Carlesimo said. "I don't think he's coming in to see me, I think the fact that it's Miami and Chicago might have a little something to do with it. Two pretty good games to come in and see the team. So I think the fact that I'm here is nice, but I don't think he was sitting in Moscow the other day saying, 'You know, I've got to go see P.J.'" ... Miss America, Mallory Hagan, sang the national anthem. Hagan, New York's first winner since Vanessa Williams, said she has moved six times since first coming to Brooklyn and hopes to return once her yearlong duties are completed. "I was Miss New York when the Barclays Center opened up and so I was looking forward to being able to be here, and now it's even better that I'm Miss America and Brooklyn is where I came from," she said. ... The Heat signed Chris Andersen to a second 10-day contract and signed Jarvis Varnado for the remainder of the season.