Tyler Seguin and David Krejci also found the net for Boston, which unleashed an offensive assault that saw them fire 50 shots in a game for the first time in three years.
Bruins goalie Anton Khudobin was also extremely busy, turning aside 45-of-47 tries by the Senators as the Bruins, seeded fourth in the Eastern Conference, took a second straight win.
Andre Benoit and Colin Greening scored for fifth-seeded Ottawa, which dropped a second consecutive game.
Robin Lehner was able to stop 47 of Boston's 50 shots in the loss.
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