After two games in this Eastern Conference quarterfinal series left the Washington Capitals and Boston Bruins wondering where their offense went, both rediscovered the ignition to their scoring touch Monday night in a game that also saw the animosity between the two clubs ratchet up.

Game 3 at Verizon Center featured more goals than the previous pair of contests combined, but as the series started to loosen up offensively, it was the Capitals who wound up on the losing end. Boston captured a 4-3 win — and a 2-1 series lead — thanks to Zdeno Chara’s goal with 1 minute 53 seconds remaining in regulation.

The Bruins also found success in getting under the skin of Washington players. Efforts to start fracases after whistles picked up as the game progressed. One reaction, by the Capitals’ Nicklas Backstrom as time expired, may prove costly moving forward.

Backstrom received a match penalty for cross checking Rich Peverley in the face after the Bruins forward tripped Alex Ovechkin. Match penalties come with an automatic suspension, pending review by the NHL’s department of player safety headed by Brendan Shanahan.

“They gave him a match but I think the league will review it and rescind it. If you seen it, it was not that bad,” said Coach Dale Hunter, who was asked how he thought the Capitals dealt with the various attempts to instigate by Boston. “We can handle it. They want to have the scrums more and the physical play after the whistles and stuff to try to take our skill guys off their game, but the guys battled back.”

A few players said Boston’s strategy of trying to fluster them might have been successful. Backstrom, who was not asked specifically about the penalty after the game, said he believes the Capitals need to “handle it better.”

Said Troy Brouwer: “It might’ve [worked]. I know it worked for them last year in the finals. We have a lot of guys that are going to not get involved with that because, for us, that’s unnecessary. We don’t need to be playing after the whistle. Our focus is in between the whistles.”

Before the flare-ups at the end of regulation, it appeared as though this contest — which saw Washington get goals from Alexander Semin, Ovechkin and Brooks Laich — would be destined for overtime just like the others.

As time ticked down in the third period with the score tied at 3, Chara teed up a shot from the top of the right faceoff circle. It might have been harmless, but the puck deflected off the stick of defenseman Roman Hamrlik and past rookie netminder Braden Holtby (25 saves) for the deciding tally.

“The last goal — it’s just a tough break,” Holtby said. “Hammer tried to — he was turning, and obviously wouldn’t want to deflect it. But it came pretty quick off the stick and a perfect deflection. Those are goals that happen.”

This contest was the first of the series in which Holtby and Tim Thomas (29 saves) found themselves facing frequent up-and-down action and quality scoring chances. Both teams seemed poised for a breakout at some point, and more than six minutes of four-on-four play created plenty of open ice for them to work with.

While Ovechkin recorded a goal for Washington during a four-on-four, the Bruins took advantage of that space and would score a pair: Chara’s game-winner and their first tally of the night by Peverley early in the second period.

“We just have to make sure we don’t miss assignments in our zone,” Laich said. “I mean, the last goal, I don’t know if they tipped it or it hit our guy, so you go to block a shot and it goes off you and into the net. I mean, sometimes you can’t defend against bad luck, but we certainly don’t want to give up goals four-on-four.”

Although Boston rallied numerous times, it was the Capitals who took charge in the early going. Semin scored the first power-play goal of the series to give the Capitals a 1-0 lead 16 minutes into the opening frame. Circling in the high slot, Semin turned and released a wrist shot that found its way through traffic to beat a screened Thomas between the pads.

Tempers flared at the end of the first period, resulting in penalties to Backstrom and Milan Lucic and two minutes of four-on-four play at the start of the second that brought an offensive outburst.

That stretch included Peverley’s shot that Holtby couldn’t handle, 35 seconds into the middle frame, to even the score at 1. Washington regained the lead on the ensuing shift, though, when Ovechkin ripped a shot from the right faceoff circle that seemed to catch Thomas off guard to make it 2-1 just 13 seconds after Peverley’s tally.

Bruins fourth-liner Daniel Paille made it 2-2 at 9:38 of the second when he was left unattended in front and managed to gather a rebound and fire it into an open cage.

As the two teams continued to press, animosity grew. Lucic and Laich exchanged words and shoves when lined up for a faceoff until the Bruins forward knocked the latter over. Both players received minor penalties for unsportsmanlike conduct.

“I mean, sometimes that comes in the first game, and sometimes it takes incidents and moments as the series moves on to develop it,” Laich said of the chippiness. “You know, there was more stuff, extracurricular stuff after the whistles. We kind of don’t want to get caught up in that.”

At the start of the third the Bruins took their first lead of the game and the series on a goal by veteran winger Brian Rolston. With the Capitals scrambling in front of their net Boston players flung the puck at the net from any and all angles, looking for rebounds or helter-skelter plays. Rolston managed to poke the loose puck between Holtby’s pads for a 3-2 Bruins lead just 62 seconds into the frame.

Laich answered to make it 3-3 with 14 minutes gone in the third when he showed incredible patience to beat Thomas cleanly one-on-one. Washington wouldn’t manage to find a way to regain the lead, though.

“It’s tough, but again, it’s nothing to lose,” Ovechkin said. “You know, series not ended, and somebody have to win, somebody have to lose. . . . I think we play great today but we make a couple mistakes and it costs us a goal. That was great battle, but we lost.”