NHL

Staying out of penalty box key to Rangers series rally

WASHINGTON — It was discipline that won out over aggression, a noble approach to a game played with such merciless intensity.

At least that’s the way it worked out for the Rangers, taking their first-round playoff series against the Capitals with last night’s 5-0 Game 7 win at the Verizon Center, advancing them to the second round against the Bruins starting Thursday.

Through the final two games of this series, the Rangers allowed the Capitals’ No. 1-ranked power play just 4:00 of total ice time, none of which came in Sunday’s 1-0 Game 6 win, and 2:00 of which was buried in garbage time last night after the Rangers were already up 5-0.

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“I think the key to the last few games was the discipline,” said goalie Henrik Lundqvist, now climbing the netminder pantheon with eight career playoff shutouts. “We didn’t let their power play come out on the ice. That’s when they really feel good about their game and that’s really when they score the most goals.”

In the three games the Capitals won in this series — all of them at home — they scored one power-play goal in each. In the four they lost, they didn’t get any.

“We were pretty disciplined and didn’t retaliate, which was something I think was a key in the series,” said defenseman Ryan McDonagh, who was plowed face-first into the boards by Alex Ovechkin 8:30 into the first period when no penalty was called and no physical rebuttal was made by the Blueshirts. “We tried to keep them off the power play, which we found out early on that they can strike at will. It was just a good job by everyone.”

* Chris Kreider played in his second straight game up front, playing his most assertive game of the series by utilizing his speed over 7:53 of ice time. His highlight came 13:19 into the first period on a breakout through the neutral zone, when he gained the blue line than made a smooth little drop pass for Arron Asham, who netted a slap shot to give the Rangers a 1-0 lead.

The 21-year-old rookie played in Game 1, but was scratched from Games 2 through 5 after Brian Boyle returned from a right-knee injury. He got back in for Game 6 at the Garden, but played a game-low 4:05.

With Ryane Clowe still dealing with what is presumed to be his second concussion in two weeks, it’s more than likely Kreider will stay in the lineup against the Bruins.

* A lot was made of the Rangers having never won a Game 7 on the road before last night, but the loss brought the Capitals’ Game 7 home record to 2-7.

* Rangers’ rookie forward J.T. Miller is no longer skating with the taxi squad after he was called up from the AHL’s Connecticut Whale early in the postseason. Miller, 20, was sent home so that his previously injured left wrist can heal.

* Marc Staal participated in the Rangers optional skate yesterday morning, but sat out for the fourth straight game because of his injured right eye.

bcyrgalis@nypost.com