They made the most of their opportunities -- including Kessel's shootout goal, which rolled off his stick and somehow into the net -- in rallying from a two-goal deficit to pull out a 3-2 win over the Buffalo Sabres.
"I came down and I tried to deke and I lost it," Kessel said, describing how he watched the puck slip in through Ryan Miller's legs. "You can't get any luckier."
Good fortune was the only thing the Bruins were missing in a game in which they outshot the Sabres 37-23, but trailed 2-0 after two periods.
Besides being foiled several times by Miller, the Bruins also had difficulty finding the net. One example of that came early in the second period, when Glen Murray, set up alone in the slot, snapped a shot wide.
"I didn't think we were playing bad for the whole game. There was only one thing missing, and that was the finish," Bruins coach Claude Julien said. "I guess you eventually get rewarded for staying with it, which is what I think Phil Kessel did."
The win snapped the Bruins' two-game losing streak, and made up for their 4-2 loss at home to Buffalo on Tuesday. Boston also moved into seventh place in the Eastern Conference standings, a point ahead of the idle New York Rangers, and three up on the Sabres.
Kessel scored the lone shootout goal, as backup Alex Auld stopped all three Buffalo shooters. Auld, making his first start since Jan. 17, sealed the win when he foiled Derek Roy's backhander at the right post.
Playing their third game in four nights, the Sabres ran out of gas, particularly in the third period, when they were outshot 17-1. Their one and only shot came with 2:45 left when Ales Kotalik's weak shot from the right circle was easily stopped by Auld.
"We didn't have much for legs. We put ourselves in a bad spot," Sabres coach Lindy Ruff said. "It was disappointing. We didn't deserve a point tonight."
Ruff, though, did credit Miller, who stopped 35 shots but squandered a chance to win his 100th career game.
Miller had a different perspective.
"I'm not really happy right now," Miller said. "It's just unacceptable. We're not letting ourselves off the hook on this one."
The Sabres, who have now lost five times (17-2-3) when leading after two periods, appeared to be in control when Vanek scored with 38 seconds left in the second period to put the Sabres up 2-0.
The Bruins improved to 2-17-1 this season in games when they're trailing after two periods.
"There's no doubt, this is great for the confidence," Julien said. "We're a team that after two periods down haven't had much success. This is a great boost."
Murray returned after missing 19 games with a hip injury. Murray played a role on Chara's goal, providing a screen in front. ... Sabres RW Drew Stafford didn't return after hurting his right ankle during a collision with Chara midway through the third period. ... Spacek scored on the power play, meaning the Bruins have allowed 12 power-play goals in their past 10 road games. Of the 48 power-play goals they've allowed, 33 have come on the road.