Avery Bradley hit the go-ahead three-pointer with 1:24 left in regulation and Boston slipped out of Denver with a 100-99 victory at Pepsi Center.
"He missed one last night that he thought he should have made. He made up for it tonight," said Celtics head coach Brad Stevens.
Jameer Nelson poured in a game-high 23 points on 9-of-20 shooting for the Nuggets, who dropped their fifth straight contest. Arron Aflalo picked up 20 points and J.J. Hickson totaled 15 with 14 rebounds.
The Celtics were behind 61-49 with 7:32 remaining in the third quarter but eventually took a 70-69 lead on a Marcus Smart free throw with 2:06 left. Marcus Thornton's jumper gave them a 75-74 edge after three.
Bass later hit two from the line and Boston was ahead 86-80 with 7:34 left in regulation, but Hickson, Afflalo and Nelson hit shots -- the last one a triple by the former Saint Joseph's star who was acquired by the Nuggets from the Celtics 10 days ago -- and Denver was back on top 87-86.
Each side traded turns with the lead until Bradley's shot from beyond the arc made it 98-96. Wilson Chandler then missed the second of two from the line and Nelson missed a jumper before Bradley connected on a two-pointer for a three- point Boston edge.
Hickson made a layup with 14.7 on the clock, and though Evan Turner missed both free-throw tries, Nelson couldn't get a step-back jumper to go with 1.4 remaining.
"We're trying to find a way," Faried said. "We're trying to fight and claw, but we didn't claw enough. We didn't have enough fight in us. We had the last shot. When Jameer put it up, we thought it was going to go in. We even tried to get the rebound to put it in, but too little too late."
Nelson scored 11 points and the Nuggets led 28-20 after one quarter, and were up by as many as 10 in the second quarter before taking a 48-42 edge to the break.
Hickson and Kenneth Faried converted dunks in the first two minutes of the third and Denver was ahead 52-42. They maintained that comfortable margin for several minutes before Boston began its comeback.
"It's great from a progress standpoint and you hope you can build off of it," Stevens said of winning back-to-back nights on the road. Boston's six-game west coast swing continues Sunday in Oakland against red-hot Golden State.
Boston had lost five straight in Denver, since claiming a 114-76 decision on Feb. 23, 2009 ... The Celtics also snapped a losing clip of 28 straight defeats when trailing by 12-or-more points at any juncture in a game ... Nuggets forward Kenneth Faried finished with 11 points and 14 rebounds in defeat ... Turner scored 10 points and dished out six assists for Boston ... The contest featured nine ties and 17 lead changes.