Patrice Bergeron netted the game-winning goal with 1:22 remaining in overtime, giving Boston a 2-1 victory over Ottawa at TD Garden.
After a right-circle faceoff win, Bergeron redirected a point drive from Dennis Seidenberg between Ottawa goaltender Robin Lehner's pads. The puck trickled through the crease and appeared to barely make it totally across the goal line before eventually being pushed further into the net.
There was no audible whistle to halt action, and play was not stopped until an official behind the cage waved his hands to indicate a review. After a brief check, the goal stood to end the contest.
"I thought for sure it was in, especially after that second kick at it," Bergeron said. "Marshy (Brad Marchand) was standing right there. He said it was definitely in after the second time."
Nathan Horton notched the other goal and Tuukka Rask stopped 30 shots for the Bruins, who have won five in a row and eight of their last 10.
Jim O'Brien tallied and Lehner made 44 saves for the Senators, who saw their five-game win streak halted.
The Bruins broke through at 5:48 of the second period, as Horton's off-speed redirection along the ice slid through Lehner's pads as he overcommitted to the shot.
Seconds after making a pad stop against the left post on an Ottawa advantage, Rask was prone in the crease as the Sens winger kept working and eventually poked a loose puck home for a 1-1 game with 5:22 left in the middle period.
Both sides created multiple quality chances in the third period, but could not break the deadlock.
Milan Lucic was called for a delay-of-game after closing his hand on the puck behind the Ottawa net with 31.6 seconds left in regulation, but the Bruins enjoyed the majority of scoring chances while shorthanded.
"Coming into a building like this with probably the hottest team in the conference, we played them toe-to-toe and that's something to take away," Senators captain Daniel Alfredsson said."
Boston has beaten Ottawa in 15 of the last 19 meetings since the start of the 2009-10 campaign ... Lehner's performance came on the heels of Ben Bishop's 44-save effort in a 2-1 shootout win against Montreal ... Both clubs are back in action on Saturday, as Ottawa plays in Philadelphia and Boston hosts Tampa Bay.