Nikola Jokic and Jamal Murray combined for 69 points as the Denver Nuggets halted Boston’s unbeaten home start to the season with a 102-100 win.
The NBA champions ended their rivals’ 27-game streak, which stretched back to last season with a 20-0 record this season.
Two-time NBA Most Valuable Player Jokic finished with 34 points, 12 rebounds and nine assists.
Murray led the Nuggets’ scoring with 35 points from 15 of 21 shooting.
“During the season you’ve got to find ways of motivating yourself and your team, and them not having a loss at home really motivated us,” he said.
“We just wanted to come here and bring the right energy regardless.
“[It’s] just a lot of fun when it gets competitive and physical like that. Just a really good win on the road.”
Derrick White led Boston’s scoring with 24 points while Jayson Tatum added 22 and Kristaps Porzingis 21.
The Celtics had a 12-point lead during the second quarter but Denver edged ahead 99-98 with three minutes and 36 seconds remaining.
Tatum missed an opportunity to tie the game late on and the Nuggets held on for victory.
Elsewhere, Devin Booker hit 52 points as the Phoenix Suns beat the New Orleans Pelicans 123-109.
The Suns point guard had three-pointers as he hit 18 of 30 from the field, while Kevin Durant added 26 points for the Suns with Bradley Beal scoring 13.
The Los Angeles Lakers’ revival came to an end with the 17-time NBA champions thumped 130-112 by the Brooklyn Nets.
The struggling Lakers had back-to-back wins over Oklahoma City and Dallas this week suggesting they might have turned a corner, but Cam Thomas led the Nets scoring with 33 off the bench, including four three-pointers.
Anthony Davis and LeBron James led the Lakers scoring with 26 and 24 points respectively.
And reigning NBA MVP Joel Embiid made it 19 straight games with 30 points or more, hitting 36 points as the Philadelphia 76ers cruised past the Orlando Magic 124-109.
