OTTAWA - P.J. Axelsson scored on Boston's fifth shootout attempt after Tim Thomas stopped all five Ottawa shooters in the NHL-leading Bruins' 4-3 victory over the Senators on Thursday night.
Axelsson secured Boston's fourth straight victory when he put a backhander between Brian Elliott's pad after the Ottawa goalie stopped Boston's first four shooters.
Chuck Kobasew drew Boston even at 3-3 with a power-play goal with 4:02 left in the third. Kobasew put a rebound past Elliott from the goalmouth during a double minor to Vermette to tie it after the Bruins had allowed three goals to blow a 2-0 lead.
Blake Wheeler assisted on Kobasew's goal after opening the scoring with his 15th goal on a power play 11:46 into the first period.
Boston captain Zdeno Chara, who also assisted on Kobasew's goal, made it a 2-0 lead with his 12th midway through the second.
Nick Foligno scored later in the second and Alfredsson had a goal and an assist in the third, setting up Spezza's power-play goal at 8:33 that put Ottawa up 3-2.
Thomas made 19 saves.
Elliott stopped 26 shots in his 10th start in 11 games
Elliott made a pair of big saves on Bruins defenceman Dennis Wideman in overtime, including a big glove save 1:10 into the extra period as Boston failed to take advantage of a power-play opportunity after Ottawa's Mike Fisher drew an interference penalty at the end of regulation.
Thomas robbed Fisher with a sprawling pad save later in overtime.
After Wheeler opened the scoring, Chara made it 2-0 midway through the second. The Boston captain drove a slap shot from the point past Elliott for his 12th goal at 10:27.
Ottawa lost its fourth game in a row overall and second straight under head coach Cory Clouston.
The Senators had been shut out twice in their previous three games, including a 1-0 loss to Los Angeles on Tuesday night in Clouston's NHL debut.
Foligno scored a highlight-reel goal 15:54 into the second.
After receiving Bell's pass at the Boston blue line, Foligno drove the left side then cut toward the slot, moving past defencemen Andrew Ference and Wideman to reach around and put a backhand past Thomas before tumbling along the ice.
Alfredsson scored his 15th goal early in the third to tie it at 2-2.
Notes: Bruins LW Milan Lucic did not play after sustaining an undisclosed foot injury Wednesday night in a 3-1 win in Philadelphia ... Senators C Dean McAmmond was a healthy scratch for the second time in four games ... Ottawa is back at Scotiabank Place on Saturday night, facing the Buffalo Sabres (7 p.m., CBC, Team 1200). Fewer than 2,500 tickets remain for the game.