Bergeron scored 24 seconds later to get Boston within 2-1. He has 21 goals in 32 games after returning from a lower-body injury on Dec. 9.
"Playing with those two guys (Marchand and Pastrnak) makes my job real easy," said Bergeron, who has scored in five straight games. "I'm trying to take care of the details of the game and go on the attack, and from there, simplifying our game. We're used to each other. We know where to be. I'm trying to get open for them to find me."
Gaudreau's centering pass deflected off the post and then off Halak to give Calgary a 3-1 lead at 3:23. It set a Flames record for the fastest three goals to start a game, quicker than the 3:29 it took against the Los Angeles Kings on Jan. 27, 1986.
"It was 3-1 with, what, 55 minutes left in the game, so it's basically a whole game there," Calgary forward Matthew Tkachuk said. "You can't take it for granted, that lead, even though it was nice to get off to a good start. Then they got three unanswered goals."