BOSTON (AP) - About the only breaks Ryan Miller had in the third period came when his teammates scored a pair of goals.
Miller made 18 of his 38 saves in the final period as Buffalo earned its fifth win in seven games and continued to climb toward playoff contention in the Eastern Conference.
"Up until the All-Star break we've got to run the table to be around where we want to be," Miller said. "That first half of the season, we had some efforts that I thought were pretty good but we weren't getting the rewards. That's a frustrating feeling. So it's been good to get that positive feeling."
The Sabres were coming off a 2-1 overtime win against Montreal on Tuesday and continued to play well, holding the Bruins scoreless on four power plays.
"It's a great win for us against a good team," said Vanek, who also had an assist on Pominville's goal that put the Sabres up 4-2 with 3:20 left. "Boston always plays us tough, especially here. Two timely goals in the third period."
Tyler Ennis had two assists and Nathan Gerbe and Cody McCormick also scored for Buffalo, which won for the third time in five meetings with Northeast Division rival Boston and improved to 21-20-5 overall.
"From start to finish, I don't think there's much to say here except we were totally flat tonight. From the first player to the last," Boston coach Claude Julien said. "We came out flat tonight and never seemed to find our game. Even in the third period - you're coming in there tied and you've got an opportunity in 20 minutes to seal your fate and it just wasn't happening tonight."
Tuukka Rask had 29 saves for Boston, which was 0 for 4 on the power play and fell to 18-2-3 when scoring first.
The Bruins led by a goal twice but couldn't hold off the Sabres, who got goals from Vanek and Pominville in the third and another great night from Miller as he started his 23rd straight game.
Vanek came in on a 2-on-1 and kept the puck, snapping a shot high to Rusk's stick side for an unassisted goal with 14:47 left. Vanek added an assist with a centering pass from the corner and Pominville was able to get a stick on it while crashing the net.
"We need him to produce. There's no getting around it," Miller said of Vanek. "It's good to see him getting pucks to the net."
Miller robbed Mark Recchi and Marc Savard on great scoring opportunities in the second to keep it tied at 2 and allow the Sabres to win it in the final period.
Recchi was all alone in front and swept a backhand right into Miller's glove midway through the period, then on a 2-on-1 Savard fired a shot that Miller got just enough glove on to tip it wide and keep it tied at 2.
Sabres defenseman Steve Montador saved a goal early in the third when the puck got behind Miller. Montador was able to sweep it out of the crease before it could cross the goal line.
The Sabres tied it with 9:24 left in the second on a power-play goal by Gerbe off a crossing pass from Tyler Myers. The puck movement got Rask off balance and he had no chance to stop Gerbe's one-timer from the circle. It was the third goal of the season for Gerbe, a former Boston College player.
Seidenberg gave Boston a 1-0 lead in the first, but McCormick tied it early in the second when he slapped in his own rebound after hitting the post for his seventh goal of the season.
Notes: Play was stopped for several minutes early in the second period to replace a pane of glass in front of the goal judge. ... Savard's assist on Seidenberg's goal was the 499th of his career.