The Cleveland Cavaliers' 12-game winning streak came to an end on Sunday night with a 108-93 loss to the Indiana Pacers.
The Cavaliers have risen to top of the eastern conference thanks to a recent run including wins against rivals Los Angeles Lakers and Milwaukee Bucks.
But Andrew Nembhard, who top scored with 19 points, and Pascal Siakam, who hit 18 points, combined to help the Pacers to victory.
It was the Cavaliers' first defeat since 8 December and just their fifth from 38 matches this season.
"There was nothing to lose, this is the best team in the league right now," said Nembhard.
"We had to play hard, play together, and put some more physicality in the game on the defensive side of the ball, and play off of that."
The Cavaliers, who are 40.3% from three pointers this season, made just 11 (26.8%) of 41 against the Pacers.
Reflecting on the loss, Cleveland coach Kenny Atkinson said: "What disappointed me was our first half was phenomenal, defensively, and then the second half, we fell off. We couldn't sustain our defence."
NBA results - 12 January
Detroit Pistons 123-114 Toronto Raptors
Minnesota Timberwolves 125-127 Memphis Grizzlies
Portland Trail Blazers 98- 119 Miami Heat
NY Knicks 140-106 Milwaukee Bucks
Dallas Mavericks 101-112 Denver Nuggets
Washington Wizards 95-136 Oklahoma City Thunder
Orlando Magic 104-99 Philadelphia 76ers
Boston Celtics 120-119 New Orleans Pelicans