And from the start no one in the howling sellout crowd would let Washington forget just how precarious its predicament was. There were ear-splitting chants of “Let’s Go Rangers.” The fans serenaded star goalie Henrik Lundqvist after every spectacular save — “Henrik!” — and banged their electric-blue thunder stix.

But out of that cauldron of noise and emotion the Caps escaped with their playoff hopes still intact. Forward Alexander Semin scored a pair of first-period goals and rookie goalie Simeon Varlamov matched Lundqvist save for save, earning his first career shutout. It all added up to a 4-0 victory for Washington, which now has life heading into Game 4 at the Garden on Wednesday night at 7 p.m.

“In the beginning of the season I was playing at [AHL affiliate] Hershey,” said Varlamov, who became just the fourth NHL goalie under 21 to record a postseason shutout. “I not only didn’t think about the playoffs, I didn’t think I was going to play in the season at all.”

The home team has yet to win in this odd series. New York took the first two games in the District. But with their fans roaring for them to put the Caps away the Rangers faltered, taking seven penalties in the first two periods alone and nine overall. Brooks Laich scored on one of those power plays at 11 minutes, 29 seconds of the second period to put Washington in complete control at 3-0.

New York forward Sean Avery — who always plays on the edge — went too far on this night, taking four penalties, including inexcusable roughing calls for punching both Varlamov and Caps defenseman John Erskine in the face. Avery was also whistled for goalie interference on Varlamov. Erskine skated away from that first altercation, drawing raves from his teammates. He later earned some revenge by driving Avery into the net — although also admitting the Rangers forward embellished the play.

“I’ve seen him do that enough in other playoff series and games and that’s his play — he wants to get on the goalie and get under his skin,” said Erskine, adding that the swing Avery took at him “wasn’t that hard a punch.”

Earning his second playoff start in place of Jose Theodore, the 20-year-old Varlamov gave his team a chance to win. That’s all coach Bruce Boudreau can ask of a player who had yet to make back-to-back starts even during the regular season. Varlamov stopped all 33 New York shots and has not allowed a goal in 112 minutes, 16 seconds since Ryan Callahan’s first period goal in Game 2 at Verizon Center.

The game is obviously, different [in North America], Varlamov said through a translator. “The only thing that is the same is the pressure from the fans of the other team. That’s the same there as it is here at Madison Square Garden.”

Varlamov was also helped by countryman Alex Ovechkin, a force all over the ice in his best game of the series. He assisted on both of Semin’s goals. Late in the second period, Ovechkin tracked down a streaking Lauri Korpikoski on a shorthanded break and made a diving sweep check to save an easy scoring chance.

If possible, teammate Nicklas Backstrom was even better while centering a line with Semin and Tomas Fleischmann. His two passes to Semin and Tom Poti — the latter a power-play goal with 85 seconds left — were world-class efforts.

“I don’t know if there are words,” Boudreau said, when asked about Backstrom’s play. The set-up to Poti was “as good as any pass I’ve ever seen.”

Now, the task is to do it again in front of another raucous sellout crowd of 18,400 — or head home to the District for the second straight elimination game in Game 5 of a first-round series. But for the first time in the series, the Caps actually executed the blueprint they believe will lead them to the second round.

“I think tonight was a good glimpse of how to be successful,” said defenseman Brian Pothier. “It worked for us tonight because we were willing to do the little things — not retaliate, getting into those hard areas to fight for rebounds.”