The Bruins also dodged a bullet when Brad Marchand appeared to avoid injury after a pair of big hits.

Boston’s captain did not come out for the start of the third period, but eventually returned and finished the game.

Marchand crashed into the boards behind the net after a thunderous check from Josh Manson and later took what appeared to be an elbow to the head of Mikko Rantanen, who was penalized for interfering with play.

“Brad is doing well,” Montgomery said. “Just a spasm.”

Charlie Coyle, who scored his first of the season, said it was a “huge” boost to see Marchand return to help finish off Colorado.

“You never know what’s going on, your captain doesn’t come out right away and all of a sudden you kind of get a shock when you see him,” Coyle said. “And I think if it were up to him, every time he would come out, no matter what happens of course… He’s our leader, he’s one of our best players, and we need him in the lineup and that is always the case. it gave us a little jolt in life to see him there again and just his drive, his motivation to be there with us.

The win was also the first as a Bruin for Joonas Korpisalo, who was solid throughout the match but especially sharp in the third period when he knocked back 13 of 14 shots.

The Avalanche scored all three goals on the power play: one each from Ross Colton, Cale Makar and Rantanen.

“Korpy was really good for us tonight,” said defenseman Hampus Lindholm.

The Bruins opened the scoring when Cole Koepke redirected an Andrew Peeke snapper past Alexander Georgiev (20 saves).

After Colton tied the score on a nice give-and-go with Rantanen, Coyle restored the lead with a power play goal.

Mason Lohrei collected Hampus Lindholm’s dump, drove to the top of the right circle and sent a pass through the skates off the tape of defenseman Samuel Girard Coyle for the tap-in.

“I didn’t know how it was going to happen, but I knew he saw me, and I tried to present myself and Mason as a pretty skilled player and he thought I was pretty good,” Coyle said. “I didn’t have much to do with that. He put it on a platter.”

The Bruins increased their lead to 4-1 with a pair of banging goals.

With Rantanen in the box for his foul on Marchand, Hampus Lindholm jumped deep and made a nice pass across the blue paint to David Pastrnak, who went all Bobby Orr and punched the puck home as it flew through the air in front of Georgiev .

Hampus Lindholm hit one home just 13 seconds after setting up Pastrnak. Lindholm wristed one from the top of the circle that Georgiev never saw, thanks in part to a nice screen from Johnny Beecher.

Makar cut the score to 4-2 after two with an absolute rocket from the blue line.

Rantanen’s strike five minutes into the third gave the Avalanche life before Marchand’s return boosted the Bruins’ closing efforts.

Johnny Beecher created an empty net goal.

Hampus Lindholm said the fast start was key for the Bruins.

“That’s something we’ve definitely emphasized as a team,” he said. “I mean, their team has a lot of attacking power and with the altitude and everything, we really wanted to make sure we got a good start and then just try to keep it going for the full 60.”

Jim McBride can be reached at [email protected]. Follow him @globejimmcbride.