Not only did the victory snap Boston's six-game losing streak, but it also gave the Bruins their first win in seven shootouts.
"It's been a long time coming," Thomas said. "It's nice to know what the teams that have been beating us in the shootouts feel like."
On Boston's first shot in the shootout, Bergeron glided in the front of the net and snuck the puck past Ottawa goalie Ray Emery. Thomas then stuffed Daniel Alfredsson, Dany Heatley and Spezza for the win.
The Bruins have defeated the Senators four straight times and are the only team in the NHL to beat Ottawa more than twice. Boston won only its second game in March, while Ottawa lost for the first time in three tries and fell to 7-1-1 since the Olympic break.
Thomas saved 31 shots, including 13 in the second period, to win for the first time in eight tries and improve his record to 9-7-5.
"His energy is contagious," Bruins coach Mike Sullivan said of Thomas. "Our players feel it, I feel it behind the bench. He's inspiring to everyone."
Ottawa, which entered the game as the NHL's highest-scoring team at 3.97 goals per game, fell to 0-2 against Thomas this year. Thomas saved 44 shots in a 5-0 Boston win on Jan. 30, recording the last shutout against Ottawa.
After being held to just five goals in their last four games, the Bruins took a 1-0 lead 1:29 into the first period when Brad Boyes poked a rebound behind Emery.
Bergeron extended Boston's lead to 2-0 just 1:09 into the third period when his pass from behind the net bounced off Emery's stick and into the net.
After Thomas saved all 22 Ottawa shots through two periods, the Senators scored twice in less than 4 minutes in the third period to climb out of a 2-0 deficit and force overtime.
"When they made it 2-2, I just didn't have the sense that it would totally switch the other way even though they caught up," Thomas said.
A streaking Spezza received a nifty pass from Heatley in front of the Bruins' net and pushed the puck past Thomas to make it 2-1 at 7:24 of the third period.
Antoine Vermette then tied it at 2 at 11:16 on a back-handed shot from the right of the net.
"It's frustrating because we felt like we had the momentum," Vermette said. "But then we took that penalty that was hard for us to take."
The Bruins could have turned the game into a blowout early, but failed to convert on a pair of easy opportunities.
First, Sturm missed a wide-open shot from point-blank range midway through the first period. Wayne Primeau then hit the post on another wide-open attempt, this one from left of the net seven minutes into the second period.
Despite the loss, the Senators were happy to salvage a point despite falling behind by two goals.
"It was good to see us come back and keep playing hard," Vermette said. "In the playoffs, you won't take the lead every time."
Notes: Boyes ranks third in points scored and sixth in goals among NHL rookies. ... Ottawa is 17-5-2 against Northeast Division opponents, but four of their division losses have come to Boston. ... Senators goalie Dominik Hasek, who has missed nine games with a groin injury suffered at the Turin Olympics, traveled with Ottawa to Boston. ... Mark Stuart, playing in his third career game since being recalled from Providence on March 10, assisted on the Bergeron's goal to record the first NHL point of his career. Stuart was Boston's first-round draft pick in the 2003 NHL Entry Draft.
|Brad Boyes (18) ASST: Patrice Bergeron (35), Marco Sturm (23)|
1 - 0 BOS
|Patrice Bergeron (21) ASST: Mark Stuart (1)|
2 - 0 BOS
|Jason Spezza (18) ASST: Dany Heatley (46), Chris Phillips (15)|
2 - 1 BOS
|Antoine Vermette (16) ASST: Bryan Smolinski (24), Tyler Arnason (30)|
2 - 2 Tie
|1||D. Alfredsson||P. Bergeron||0 - 1|
|2||D. Heatley||M. Czerkawski||0 - 1|
|3||J. Spezza||0 - 1|
|Thomas Fitzgerald Hooking|
|Anton Volchenkov Hooking|
|Andrew Alberts Elbowing|
|Brian Leetch Hi-sticking|
|Nick Boynton Holding|
|Christoph Schubert Hi-sticking|
|Chris Kelly Hooking|
|Christoph Schubert Boarding|
|Andrej Meszaros Hooking|
|Marco Sturm Roughing|
|Bryan Smolinski Roughing|
|Bryan Smolinski Roughing|
|Chris Phillips Boarding|