The fourth line has been a Godsend for the Bruins this year. And in a promising development, that hard-working unit started to get some help from the big guns in their the 5-3 win over the Colorado Avalanche in Denver on Wednesday.

The fourth line was on the ice for three of the five goals with Cole Koepke and Johnny Beecher book-ending the scoring while the B’s struggling power play broke out for a couple of goals from Charlie Coyle and David Pastrnak to keep the 0-4 Avs reeling.

“I think that’s the best team game we’ve had so far this year and i thought it was a complete 60-miinutte effort. They’re a good team and they’re going to have their moments but I really liked out poise,” coach Jim Montgomery told reporters in Denver.

But it wasn’t as easy as it could have been for the B’s, who gave up three power play goals.

The B’s took a 4-2 lead into the third period and then earned a power play, with which they did nothing. Then, after Riley Tufte took an undisciplined penalty on Mikko Rantanen behind the play, the Avs pulled to within a goal, with Rantanen shooting it through Joonas Korpisalo on a softish goal.

But with 2:01 left in regulation and the Alexandar Georgiev, Beecher stole a bouncing puck from Nathan MacKinnon at center ice and buried it into the empty net from behind the red line.

Korpisalo had a to make one terrific blocker save on a redirection when there was still enough time for Colorado to make a push, but that push didn’t happen.

Korpisalo (21 saves) notched his first win as a Bruin and the B’s recorded their first road win of the year.

The Bruins enjoyed one of their best periods of the young season in the opening 20 minutes and probably deserved a better fate than just a 2-1 lead.

The battle level, after being called out by Montgomery, was noticeably improved, especially from the top six, where it needed to be better.

But it was the fourth line yet again that got the B’s on the board first when Koepke deflected home an Andrew Peeke shot/pass at 13:46.

But the B’s handed it right back after Tufte took a holding penalty and, 17 seconds later, Ross Colton sniped a shot over Joonas Korpisalo’s shoulder at 15:07.

The B’s got a power play earlier in the game that they did noting with, but after Pavel Zacha drew a penalty after a strong down-low shift by the first line, the second PP unit got the lead back for the B’s.

Mason Lohrei had a clear-in attempt bounce right to him before the blue line and carried the puck down to the outside of the left circle before delivering a beautiful pass to Coyle for a quick one-timer shot for Coyle’s first goal and point on the season. It was a strong night all around for Coyle.

“His legs were great. He was winning battles ,he was doing an excellent job for us in all three zones. He was the Charlie Coyle we all know and love,” said Montgomery.

The B’s came out flying for the second period and, for a while, their inability to score on some good chances made it feel like the they would be letting the Avs hang around in the game.

But two goals in 13 seconds, with Hampus Lindholm in the middle of both of them, gave the B’s some breathing space, which they would need.

After another good second line shift, Brad Marchand drew his league-leading eighth penalty of the season and took it the hard way, on a blind side interference hit from Mikko Rantanen. The B’s capitalized on the power play with Hampus Lindholm, below the left circle feeding David Pastrnak for an in-tight redirection for his fourth of the year.

On the next shift, Lindholm used a Beecher screen to sneak a shot from the outside the left past Georgiev to make it 4-1.

The Avs were able to change momentum some physical play. Matt Stienberg blew up Matt Poitras with a green light hit near the boards and Nikita Zadorov wouldn’t let it stand. He went after Stienberg, taking an extra two for slashing. Stienberg gained an angle on the Zadorov and got in a few shots in before the big man wrestled him down.

On the man advantage, Cale Makar scored his first of the year, going high on Korpisalo to cut the B’s lead to two goals.

That goal came at 11:15, and it woke up the Avs. They dominated territorially but could not get many shots on Korpisalo, who did have to make one sprawling save, with a little help from Charlie McAvoy to corral a loose puck in the crease. The B’s held a 21-11 shot advantage after two periods.

A concerning development was loss of Marchand, who left the game with about 4:00 left in the second period. On top of the Rantanen hit, he had taken a big hit behind the Colorado net from Josh Manson, who slammed him to the ice on his back. But he would return early in the third period and Montgomery said that he was fine and dealing with a “spasm.”

.