The all-too familiar refrain played on repeat in the visitors’ dressing room at Madison Square Garden on Sunday night: The Washington Capitals can’t afford to continue to take penalties, particularly those of the undisciplined and retaliatory variety, if they hope to advance past this first-round series against the New York Rangers.

Washington took five minor penalties before the final horn in Game 6 of this Eastern Conference quarterfinal, disrupting its own efforts en route to a 1-0 loss that forced a winner-take-all Game 7 on Monday in Washington.

Derick Brassard scored the game’s lone goal off a deflection, and Henrik Lundqvist finished with 27 saves for his first shutout of this series, but it was the parade to the penalty box that again sabotaged Washington’s efforts.

The Capitals have taken 31 penalties in the series. New York, which was the NHL’s least penalized team in the regular season, has been called for 19.

“It was the difference in the game,” Capitals center Matt Hendricks said. “Couple undisciplined ones, retaliatory stuff and it’s a combination of playing on the road, tough environment, not getting the calls we thought we should have been getting. But we’re not that hockey team. We’re not that type of team. We’re a disciplined hockey team. We need to stay disciplined.”

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In each of the past four games the Capitals have taken at least two more minor penalties than New York. In each game, the extended shorthanded stints have thrown them off their game plan.

For the first time in the series, though, the Rangers didn’t have to kill a single penalty because they weren’t called for an infraction until a pair of roughing minors at the final buzzer. Frustration with the discrepancy in calls has built up for the Capitals, and it appeared to reach a boiling point in Game 6.

“We took penalties. We deserved some; we didn’t deserve some. I can’t believe that they didn’t get a penalty tonight,” winger Troy Brouwer said. “Seems a little bit outlandish, but that’s how it goes. That’s how the series has kind of gone on. We’re not helping ourselves, either. We take untimely penalties.”

After looking out of sorts early on in the previous two games in New York, the Capitals got off to a more crisp start in Game 6. Washington’s defensive support made for clean breakouts and short offensive possessions for the Rangers — until the trips to the penalty box began.

The Capitals took three minor penalties in the final 9 minutes 59 seconds of the first period, beginning with Jack Hillen receiving a roughing minor for a retaliatory shove of Ryan Callahan. Then they took two more in rapid succession — Karl Alzner for delay of game and Eric Fehr for elbowing — that led to a 44-second five-on-three for New York.

Luckily for Washington, the Rangers’ power play remained incompetent, making poor decisions with the puck, passing up opportunities to shoot and making it easy to anticipate its movements. New York recorded just five shots on the six minutes of power-play time in the first, none on the two-man advantage. After two more unsuccessful opportunities in the third, the unit is now 2 for 26 in the series, but there’s a sense that the Rangers’ power play is bound to break out at some point.

“Our PK’s done great. It’s holding us in this series,” said Braden Holtby, who finished with 28 saves. “Tonight shouldn’t have been so lopsided. It shouldn’t have. We all know that. Everyone can see that. That part is frustrating, but I thought our guys did a very good job of keeping their composure through it. We won’t use it as an excuse.”

New York took a 1-0 lead with 9:39 elapsed in the second period when Brassard’s shot skipped off the left glove of defenseman Steve Oleksy and into the net. Holtby likely didn’t even see the shot because of a screen in the form of 6-foot-4, 213-pound Rick Nash, who was positioned perfectly atop the crease.

Immediately after the Rangers pulled ahead, the game took on a frantic end-to-end pace as the teams traded chances. Arguably no one was more noticeable in the latter half of the second period than Alex Ovechkin.

Washington’s captain had two quality opportunities. The first came with 10:14 gone in the period, but the puck rolled off his stick as he tried to work around an outstretched Lundqvist. Then at the 15:10 mark he forced the Vezina Trophy finalist to make a flashy left-pad stop. And after Lundqvist turned his shot away, Ovechkin blocked two shots, both from defenseman Ryan McDonagh, for what was his best two-way shift of the series.

Ovechkin wouldn’t have as much opportunity to get on the ice in the third period though as the Capitals took two more minor penalties. Joel Ward was whistled for cross-checking noted pest Derek Dorsett at the end of a rush into the offensive zone and sending the Rangers forward crashing into the net just 5:34 into the final frame.

With nearly 14 minutes gone in the third came the retaliatory penalty that irritated Washington most. Mike Green and Dorsett pursued the puck into the corner, and the two players got tangled up. The Capitals said Dorsett slew-footed Green, which is when a player uses his legs or feet to knock an opponent’s feet out from under him. Green cross-checked Dorsett to the face for the play and received a minor penalty for the retaliation.

“It’s a dirty slew-foot, and we’re short-handed from it,” Holtby said. “That’s the only one I think any of us have a problem with.”

Green didn’t speak to reporters after the game, but Coach Adam Oates expressed his concern about the call.

“That play to me is the one that does concern me because it looked like a slew-foot to me and obviously that’s why Mike reacted,” Oates said. “Mike’s not that type of player, and you’re watching it. To me it looks like a slew-foot. Very dangerous play. Greenie’s one of those guys that they want to target, but to me, that’s a very dangerous play.”

For as much as the Capitals were unhappy with the play and their top defenseman being in a potentially dangerous situation, though, to have to kill off yet another penalty with 6:14 remaining in regulation while trying to mount a comeback was far from ideal.

“I’m not going to comment on what I thought [about Dorsett’s play],” Hendricks said. “But it’s a time in a point in the hockey game where we can’t afford to be in the box.”