James drove the lane and floated a half-hook runner over 7-footer Brook Lopez with one second left to give the Cavs a 90-88 victory. James is accustomed to making game winners on pull-up jumpers and lay-ups, but couldn't recall ever using that shot to beat another team at the buzzer.
"Brook did not think in his wildest years I was going to shoot that one," James said. "I got to my spot where I wanted to get to and I just trusted what I've always done. I work on those shots.
"And I just floated it up. Sometimes it's a little easier when you get someone bigger because you got to get it over top of them."
Jarrett Jack's desperation heave at the buzzer from well beyond half court hit the back of the rim and the Cavs survived to remain unbeaten at home (9-0). But it didn't come easy.
Lopez scored 22 points -- 10 in the first quarter -- and Joe Johnson had 17 points for the Nets, who have lost four of their last five.
The Nets tied the game at 88 with 15.2 seconds left when J.R. Smith fouled Johnson on a 3-point attempt. Smith got caught in a screen and tried to recover, but couldn't slow down and crashed into Johnson.
Johnson made all three free throws, setting up James' game winner.
Smith had a career-high four blocks and played well defensively throughout the night. Cavs coach David Blatt left Smith on Johnson for the Nets' final two possessions, the time of the game when James typically guards the opponent's best perimeter player.
Johnson had a potential game winner rim out with 18 seconds left while Smith was guarding him, then Smith committed the costly foul on the next possession.
"To me it says if we lose, we can blame this one on J.R.," Smith joked about guarding Johnson on the final two possessions. "If God forbid we lose that game, a lot of wandering eyes in the locker room."
Johnson's earlier 3-pointer gave the Nets an 83-76 lead, but they went scoreless for 3 1/2 minutes while the Cavs fought back. The Cavs were playing their third game in four nights while the Nets were off the last two days after suffering another tough loss at the Oklahoma City Thunder on Wednesday.
"We had our chances down the stretch and didn't take advantage of them," Nets coach Lionel Hollins said. "In the end, LeBron makes a play and they win the game. It's the same thing every night. The other night it was Kevin Durant. Tonight, it was Kevin Love and LeBron. That's the nature of the game."
James and Love combined to shoot just 2 of 7 in the first and the Cavs ended the quarter shooting just 32 percent. Lopez punished the Cavs' interior defense and the Nets got whatever they wanted early, leading by as many as 12 in the first half while the Cavs struggled to find their legs after a physically draining fourth quarter Friday night at the Charlotte Hornets.
The Cavs didn't take their first lead until a 3-pointer from Love with 4:50 left in the third quarter.
"For the most part, I thought we executed great. They just made a tough shot at the end," Johnson said. "We're definitely frustrated. We work hard time and time again, and put ourselves in position to win. It's a tough game."
The Nets have played better of late following a dismal 0-7 start, but Hollins knows he's still undermanned on many nights. This was one of them.
"I don't try to analyze everything," Hollins said. "I see it and I know what it is but what good does it do for me to stay up all night analyzing and trying to figure out how to make it different when we don't have Kevin Durant, we don't have (Russell) Westbrook, we don't have LeBron James?
"We are who we are and if we go out and play together as a team and work as a group and try to be disciplined in what we're doing we give ourselves a chance to win ad that's all you can do. If you're not good enough to win those games because of the other team's talent, you still have done all that you can do and you just go home and go to bed."
NOTES: The Nets averaged only 90.4 points through their 0-7 start, the worst in the league. They began the night averaging 102.5 points since, which ranks in the top 10 over the last eight games. ... Nets coach Lionel Hollins said Cavaliers F Kevin Love is in so much better shape that he didn't recognize him. "I was watching the tape and I had to ask who that was because he looks like he's in better shape. And I think he's probably better focused," Hollins said. ... The Cavaliers have outrebounded their opponents in 15 of their 17 games. ... The Cavs have rallied and won after trailing by double figures in five games this season.