DeBrusk, Swayman power Bruins over Maple Leafs 5-1 in Game 1

John Beecher, Brandon Carlo and Trent Frederic, into an empty net, also scored for Boston, which got 35 saves from Jeremy Swayman.

After the visitors registered the first four shots, Boston took a 1-0 lead at 2:26 of the opening period when Beecher scored his first-career playoff goal on a 2-on-1 after Joel Edmundson pinched at the offensive blue line.

Bruising Bruins forward Pat Maroon also nearly put Leafs defenceman Timothy Liljegren into Boston's bench inside a pulsating TD Garden that watched Toronto winger Max Domi cross-check and slash Marchand before the opening faceoff.

The Leafs couldn't connect on a 4-on-3 power play to start the second and Calle Jarnkrok - back in the lineup following a long injury absence - was stopped on a partial break moments later.

Toronto superstar Auston Matthews, who finished the regular season with 69 goals, beat Swayman in a race for a loose puck shortly after that, but sent his effort off the post.

Carlo blasted a shot past Samsonov with Leafs forward Pontus Holmberg screening his netminder at 5:47 for a 2-0 lead.