Khusnutdinov kept the puck on a 3-on-1 and sent a wrist shot from the right circle to the short side.
Morgan Geekie scored to extend his goal streak to six games (seven goals), and David Pastrnak had a goal and an assist for the Bruins (6-7-0), who have won two in a row and three of four. Joonas Korpisalo made 37 saves in his second consecutive start; he made 33 saves in a 5-2 win against the New York Islanders on Tuesday.
Bruins top-line center Elias Lindholm left the game in the second period with a lower-body injury after a center-ice collision with Sabres forward Jordan Greenway and did not return.
Rasmus Dahlin and Alex Tuch each had a goal and assist for the Sabres (4-4-3), who lost their third straight game, each in overtime, and remain winless on the road (0-2-2) this season. Alex Lyon made 18 saves.
Buffalo scored twice in 7:25 to tie the game in the third period.
Josh Doan cut it to 3-2 at 7:00. He knocked a rebound out of the air with his glove at the top of the crease and shot past Korpisalo.
Tuch then tied it 3-3 at 14:25. After a Sabres face-off win in the offensive zone, Dahlin fed him for a wrist shot from the left hash marks.
Geekie gave the Bruins a 1-0 lead with a power-play goal at 13:07 of the first period. He received a cross-ice pass from Pastrnak and scored blocker side with a quick wrist shot from the right circle.
Pastrnak made it 2-0 at 15:07. He stole the puck in the defensive zone, creating a 2-on-1 the other way with Lindholm, and faked a pass before shooting from the left circle to the far side.
Dahlin brought Buffalo to within 2-1 with a power-play goal at 16:01, scoring with a one-timer from the left point that got through traffic and beat a screened Korpisalo. It was Dahlin’s first goal of the season.
Mark Kastelic gave the Bruins a 3-1 lead at 19:39. He crashed the net during a scramble and stuffed home a Tanner Jeannot rebound after Lyon made the initial stop.
