The Capitals scored four unanswered goals, the last by Eric Fehr 37 seconds into overtime, to defeat the Bruins 4-3 Tuesday at Verizon Center.
"I think it says a lot about our character," Fehr said. "This team believes in ourselves ... we're a pretty confident bunch right now and we believe in the system. … We're playing together as a team, and that's why we were able to win today."
Boston has six losses (three regulation) and has led in four of them. It dropped its second in a row after winning six straight.
"We had the game in the bag and we got complacent," Bruins forward Brad Marchand said. "It's a very tough loss. ... It never should have gone to overtime; that's on us, we've got to be better. They got a lot of opportunities and they capitalized at the right time."
Washington has won four of five and seven of 10.
"We know how important it is to string some wins together," Fehr said. "To come back against a team that good means a lot, and hopefully we can keep going."
Fehr entered the Bruins zone and flipped a pass between Hamilton's legs that was gathered by Wolski in the slot. He flipped a backhand over Rask to even it 3-3.
"We needed this," Wolski said. "There have been so many times in the beginning of the season where we gave up leads. I think tonight is a big step for us. We had a great effort from the young guys that came in. They did a good job, the goaltending was great, and we're happy to get the win."
Marchand scored on a shorthanded penalty shot, and Zdeno Chara and Hamilton added first-period goals to give the Bruins a 3-0 lead.
"You can't expect to win a hockey game if you're not going to play three periods," Bruins coach Claude Julien said. "The team we played tonight was a desperate team. They came out with a vengeance in the second period and we didn't respond well.
"We don't have many 3-0 leads. Maybe we got too comfortable."
With the Capitals on a power play, Marchand scooped a loose puck in the neutral zone and headed toward goalie Braden Holtby on a breakaway. Capitals forward Alex Ovechkin caught Marchand from behind but hooked him, resulting in the penalty shot.
Marchand kept the puck on his forehand and while skating to his left sent it against the grain between Holtby's legs at 6:29. It was Marchand's 12th goal of the season, moving him into a tie for fifth in the National Hockey League.
A little more than a minute later, Ovechkin was called for interference after checking Chris Kelly, who a split-second before had passed the puck.
On the power play, Lucic sent a pass from behind the net to Krejci, who backhanded a pass to Nathan Horton, who backhanded a pass to Hamilton, whose blast from near the blue line beat Holtby at 18:30.
Washington started its comeback with two second-period goals.
Chara's clearing attempt was stopped at the blue line by Capitals defenseman Steve Oleksy, whose high shot was tapped to the ground by Ovechkin. He passed to Ribeiro on the left side, and he beat Rask 5:46 into the second.
Kundratek then scored his first NHL goal in his 24th career game, converting a pass from Fehr at 11:32, after Nicklas Backstrom won a faceoff in the Bruins' zone.
"I definitely celebrated like it was a winning goal in the playoffs," Kundratek said. "It was my first one, and I'll remember it for the rest of my life."