How it happened: Another third-quarter meltdown took the Dallas Mavericks from a sure-thing win against a team in a slump to an awful road loss for a three-game skid with now three days to stew.

The Mavs, behind Dirk Nowitkzi’s 5-of-5 shooting and 15 points in the first half, built a 40-25 lead in the second quarter and then packed their bags for home.

The Cavs (9-13) cut the lead to eight at the half to provide some confidence and then they used a 13-0 run within a larger 41-19 run to lead by as many as eight. Worse, Cleveland then outplayed the defending champs down the stretch, outscoring them 8-2 when it was anybody’s game.

Playing for the lead, Jason Terry missed a jumper and then committed a terrible turnover and Nowitzki, who finished with 24 points and was tremendous except in an ice-cold third, couldn’t hit a bank shot over Antawn Jamison.

Meanwhile, Cavs rookie Kyrie Irving took over with a brilliant drive through traffic and then the trees to give Cleveland its final margin of victory.

Rolling just days ago at a season-high six games over .500, the Mavs have some searching to do back home before leaving for a difficult challenge at Denver on Wednesday. They hope to Jason Kidd back for that one.

The Mavs set a season-high with 21 turnovers and those offset a mostly hot shooting night. Dallas finished at 47.8 percent shooting, while the Cavs shot it at just 39.8 percent.

So, in two consecutive games, Nowitzki -- who moved into 22^nd place on the NBA’s all-time scoring list, passing Elgin Baylor -- continues to find his rhythm and the Mavs lose.

What it means: Dallas drops to 14-11 and is just three games over .500 for the first time since Jan. 25. The Mavs also dropped to 5-6 on the road. With Portland (13-10) playing late, eight teams in the West have fewer losses than Dallas. Five have as many or more wins.

Play of the game: On a play that epitomized the Cavs’ winning formula over the Mavs, Anderson Varejao pulled down one of his seven offensive rebounds (and 17 boards overall) on a Ramon Sessions miss. He got it out to Irving, who split the defense and scored on a layup to give the Cavs an 87-86 lead with 2:34 to play.

Stat of the day: Take your pick: The Cavs outshot the Mavs, 93-67, but made just five more field goals. In related events, the Cavs had 17 offensive rebounds compared to the Mavs’ four.