Robin Lehner stopped 32 shots for his first career shutout and Erik Karlsson scored the lone goal, lifting surging Ottawa to a 1-0 win over Boston on Tuesday night.
It was the Senators' first victory in five games against the Bruins this season.
With the win, the Senators moved one point behind the Northeast Division-leading Bruins, who have played four fewer games than Ottawa. Ottawa won for the sixth time in seven games and sent the Bruins to their fourth loss in six.
The 20-year old Lehner, playing in just his 11th NHL game, benefited from some strong defensive play in front of him. His teammates blocked 10 shots in the opening two periods and limited most of Boston's shots to beyond the faceoff circles.
Lehner started because regular goaltender Craig Anderson is sidelined indefinitely after cutting his hand last week in a kitchen accident.
Tim Thomas made 37 saves for the Bruins, but lost to a divisional opponent for just the second time in 14 games this season.