The Cavaliers were foiled by the league's best 8-9 team and a backdown violation on Friday.
They dropped their fifth game in their last seven, 109-100, to the New Jersey Nets before 18,177 at Quicken Loans Arena.
They allowed a season-high 38 points to Nets shooting guard Vince Carter, the most a Cavaliers' opponent has scored all season. He sliced and diced his way past the Cavaliers, whose defense is getting worse as the season wears on.
The Cavaliers (11-7) trailed by 17 points in the third quarter. They stormed back with a 14-4 run midway through the fourth quarter, capped by Donyell Marshall's 3-pointer for a 90-89 advantage with 6 minutes, 9 seconds to play.
But it was all downhill from there. Despite a defensive stop on the Nets' next possession - a rarity on this night - the Cavaliers were hit with a rare "backdown violation" on their following trip down the court.
Official Bill Kennedy whistled the infraction on LeBron James - one of his season-high seven turnovers on the night - with a little more than 5 minutes to play. Kennedy said James was backing down Nets forward Richard Jefferson for more than five seconds.
"I've heard of it, but never seen it called," James said. "It was the most surprising thing at that moment. It might be the right call. I've never seen it happen at that time in the game. It took the life out of us."
The Nets (9-9) ran off nine consecutive points after the momentum-changing call and never looked back.
"That was a tough call, but it was the right call," Cavaliers coach Mike Brown said. "You can't fault the referees."
But the Cavaliers, who travel to Milwaukee tonight, can fault their lackadaisical defensive effort.
"We're not getting it done defensively," Brown said. "I'm just as much to blame as anyone in that locker room. They scored 109 points and shot 57 percent from the field. Until we figure it out, you'll see a lot of nights like this. We have to come out with the right mindframe. We can't play in spurts. They kicked our butt from start to finish."
The Nets' field-goal percentage (57 percent) and 3-point accuracy (61.5 percent) are the worst against Cleveland's "defense" all season.
Carter, who made 15 of 21 from the field, was the biggest culprit.
"Vince came out on fire," James said. "He made some 'hellified' shots in the first half. We dug ourselves a hole. We tried to make a run but it was too late."
All five starters scored in double figures for the Nets, as Jefferson added 18 and Nenad Krstic and Jason Kidd each added 16.
James fired in 32 points - his fourth consecutive game with 30 or more points. He became the first Cavaliers player to accomplish that feat since Mike Mitchell during the 1980-81 season.
Center Zydrunas Ilgauskas, who battled foul trouble the entire night, added 22 points, eight rebounds and three blocks. Forward Donyell Marshall, who fired in a season-high four 3-pointers, had 16 points and 10 rebounds.
"It's a quality win against a quality opponent," Nets coach Lawrence Frank said. "There's a formula for us to win, a certain recipe, and we're starting to get it.
"I think Vince Carter set an unbelievable tone early, and Richard Jefferson took the challenge against one of the elite players in the league."
Carter added a game-high 11 rebounds, six assists, three steals and two blocks.
"I just re-dedicated myself and whatever happened, happened," Carter said. "If I just continue to play and attack, it will all come together."
The Cavaliers travel to Milwaukee tonight, and they have lost six in a row in Milwaukee, dating back to March 8, 2002.