Drake Batherson and Dylan Cozens each had a goal and two assists for the Senators (18-13-4), who were coming off a 6-4 win against the Chicago Blackhawks on Saturday and are 5-1-0 in their past six games. Claude Giroux had a goal and an assist, and Linus Ullmark made 17 saves.
Charlie McAvoy had a goal and an assist for the Bruins (20-16-1), who have lost four of their past five games (1-3-1). Joonas Korpisalo allowed five goals on 17 shots before being replaced in the second period by Jeremy Swayman, who made 10 saves in relief.
Batherson gave the Senators at 1-0 lead at 1:30 of the first period. He received a quick touch pass from Nick Jensen in the high slot and beat Korpisalo over his glove.
Giroux made it 2-0 at 13:44. During a scramble in front, Batherson kicked the loose puck over to Giroux, who scored past Korpisalo’s right pad at the left post.
Zetterlund pushed the lead to 3-0 at 16:47 with a power-play goal. He took a pass in the bottom of the left circle and roofed a shot into the small window over Korpisalo’s right shoulder.
David Pastrnak cut it to 3-1 during a 5-on-3 power play at 19:07, scoring with one-timer from the right circle that hit off the far post and snuck past Ullmark.
Tim Stutzle made it 4-1 at 6:44 of the second period. He won a battle with Pavel Zacha for a loose puck to the left of the crease and lifted a shot over Korpisalo from his knees.
Cozens extended the lead to 5-1 just 19 seconds later. He scored on a slap shot from the right point that made its way through traffic and ended Korpisalo’s night at 7:03.
McAvoy made it 5-2 at 14:36 with a wrist shot from the top the right circle that beat Ullmark, who was screened by Michael Eyssimont.
Zetterlund scored his second power-play goal of the game on a one-timer from the top of the right circle to make it 6-2 at 17:26 of the second.