Bergeron scored the only goal in the breakaway competition and Rask stopped all three of Atlanta's shootout tries as the Bruins ended the Thrashers' four-game winning streak with a 4-3 victory at Philips Arena on Thursday night.
The Bruins led 3-2 before Maxim Afinogenov, left all alone in the slot, took his time and ripped a wrist shot past Rask and into the far corner with 41.4 seconds left in regulation. But Bergeron scored in the first round of overtime, and Rask made the goal stand up by stopping Rich Peverley, Slava Kozlov and Ilya Kovalchuk.
"We have lost several games in shootouts," said Rask, whose team ended a three-game slide that included a shootout loss and another defeat in overtime. "We wanted to make sure that didn't happen again."
Afinogenov gave the Thrashers a point for the fifth game in a row when Kovalchuk, who had already scored his 13th goal in 12 games, managed to keep the puck in the Boston zone, wheeled around and whipped a cross-ice pass. Afinogenov had time to settle the puck and rip a shot past Rask, just inside the far post, for his eighth goal of the season. He pumped his right fist and was knocked to ice by an exuberant Kovalchuk.
"He just, like, lifted me off the ice and we fell down together," Afinogenov said. "That was nice."
The Thrashers had the better chances in overtime but couldn't beat Rask.
"We did get a point. We battled back," defenseman Zach Bogosian said. "It's not the outcome we wanted, but we got a point out of it. That's kind of a positive."
Bruins coach Claude Julien was pleased with the way his team regrouped after giving up the tying goal.
"That goal at the end could have been a killer," he said. "But our guys decided that we weren't going to allow that to be the winner. Tuukka Rask came up big in the shootout."
The Bruins took a 2-0 lead after one period when Marco Sturm tipped in a shot by Mark Recchi with 5:59 gone and Michael Ryder beat Ondrej Pavelec with a wrist shot from the left circle at 18:11.
The Thrashers regrouped and tied the game in the second. Nik Antropov redirected a shot from Tobias Enstrom past Rask at 9:20 for his first goal of the season to go along with 16 assists. Kovalchuk tied it on a power play at 14:23 with a perfectly placed shot into the upper left corner off a pass from Enstrom, who picked up his second assist.
Boston, which came into the game last in the NHL on the power play, finally came through with Peverley off for hooking. Ryder scored his second goal of the night and sixth of the season at 16:45, beating Pavelec from a sharp angle.
"We knew we had to turn it around somehow," Ryder said. "We did a great job of back-checking."
Material from wire services was used in this report