Blake Wheeler had a goal in his first NHL game and Patrice Bergeron, playing in his first game in nearly a year, had an assist on Phil Kessel's goal for the Bruins.
Tim Thomas stopped 35 shots, including a late flurry in the last 10 seconds after the Avalanche pulled goalie Peter Budaj. Bergeron was in the penalty box after drawing a penalty with 1:41 remaining for tripping.
Bergeron missed all but 10 games in 2007 with a serious concussion after he was driven face-first into the end boards by Philadelphia defenseman Randy Jones.
The loss spoiled the return of Avalanche coach Tony Granato.
Milan Hejduk had a goal and an assist for Colorado, giving him 600 points for his career.
After Michael Ryder gave the Bruins a 4-3 lead early in the third period, Colorado tied it up on Jordan Leopold's shot off a rebound.
Joe Sakic had an assist on Cody McLeod's goal in the second period, giving him 1,007 in his career. He's now 26 shy of tying Mario Lemieux for 10th place on the NHL's all-time assists list.
Sakic now has 60 points in 60 career games against Boston. His assist to McLeod in front of the net gave the Avalanche their first lead of the game at 3-2, but the Bruins tied it up midway through the second on Savard's power-play goal.
A Bruins slapshot broke the glass behind the Avalanche's goal with 2:47 remaining in the second period, and the officials had the teams take an early intermission as a cleanup crew switched it out.
The Bruins and Avalanche finished up the second period and then promptly started the final 20 minutes.
Hejduk and Wojtek Wolski each scored for Colorado in the first period. Kessel and Wheeler had the Bruins' goals in the period.
Wolski's goal came on an assist from Darcy Tucker, who was signed by Colorado after the Toronto Maple Leafs bought him out of his contract during the summer.
Before the opening faceoff, Brian Leetch, Mike Richter, Brett Hull and Cammi Granato were honored with a video tribute and an ovation from the capacity crowd. The group will be inducted into the 2008 class of the U.S. Hockey Hall of Fame on Friday night in Denver.