The Cleveland Cavaliers' 15-match winning run came to an end in a thrilling 120-117 defeat by the Boston Celtics in the NBA Cup at TD Garden.
The Cavaliers became just the fourth franchise in NBA history to go 15-0 at the start of a campaign by beating the Charlotte Hornets on Sunday.
But six Celtics players, led by Jayson Tatum's 33 points, 12 rebounds and seven assists, reached double figures to inflict a first defeat on the Cavs.
Trailing by 17 points at half-time, the Cavaliers mounted a spirited comeback through Evan Mobley, who finished with 22 points, 11 rebounds and six assists.