Charlie Coyle gave Boston a 1-0 lead at 13:42 of the first period. Skating into the offensive zone, Coyle chipped the puck over the sticks of Moritz Seider and Elmer Soderblom before regaining possession in the slot and shooting to the top left corner.
"I think we dominated them, and it might be one of the top teams in the League, so we should be really proud of that," Seider said. "I think if anyone sees it different, please explain, but other than that I think we on a really good way."
Marchand made it 2-0 with a power-play goal at 11:53 of the second period. Left alone behind the left face-off circle, he skated in and scored on a wrist shot.
Erne cut it to 2-1 at 18:49. Following a turnover near the blue line, Erne spun and sent a shot that deflected off Bruins defenseman Connor Clifton.
"When I got another chance, I was going to give my team the best chance to win," Swayman said. "That's what we do as goalies, and you know, I'm excited that it worked out today."
Marchand's second power-play goal, off a rebound in front, increased the lead to 3-1 at 2:55 of the third period. Craig Smith pushed it to 4-1 at 3:30, and Pastrnak made it 5-1 at 4:34 with a one-timer on the power play.
"I think you kind of saw a little bit of the experience on that side versus a little bit of the inexperience on our side," Red Wings defenseman Ben Chiarot said. "Taking that extra second to make a play or just making better plays into pressure. They're a really good team, and we're trying to work our way up to that."