Capitals rookie goalie Braden Holtby makes a save against Rangers 40-goal scorer Marian Gaborik. (ADAM HUNGER/REUTERS)

Saturday’s goaltending matchup at Madison Square Garden was supposed to heavily favor the New York Rangers.

As it turned out, it was Washington Capitals rookie Braden Holtby who stole the show in his first start under Broadway’s bright lights, not Vezina Trophy candidate Henrik Lundqvist.

Holtby, in the biggest start of his brief NHL career, was occasionally spectacular in making 35 saves to help the Capitals leapfrog the Ottawa Senators and secure the seventh seed in the Eastern Conference playoffs with a 4-1 win over the Rangers.

“He’s a great goalie and he showed it out there today,” defenseman John Carlson said. “That was a big game for him. Everyone trusts him back there, everyone feels comfortable with him back there, but it doesn’t hurt for him to stand on his head like that going into the playoffs. Hopefully his confidence is even higher now.”

Winger Troy Brouwer added: “The guys in this room have complete confidence in him and he doesn’t have to prove it to anybody else. Just know that the guys in this room are behind him. He stood tall tonight and we feel that he’s a proven NHL goalie already even though he hasn’t been here all season. Going into the playoffs here, if he’s going to be our starter, then we’re excited especially with the performance he put forth tonight.”

The victory sends the Capitals — and Holtby — into the postseason confident after closing the regular season with convincing back-to-back victories. Washington will open the playoffs against the second-seeded and defending Stanley Cup champion Boston Bruins, likely on Thursday.

It remains to be seen who will be in net for Game 1 at TD Garden, but it could be Holtby depending on the health of veterans Tomas Vokoun and Michal Neuvirth.

Vokoun is battling a pulled groin muscle and has not skated with the team since March 29th. Neuvirth, meantime, did not travel with the Capitals to New York but worked out off the ice Saturday in Arlington, according to a spokesman. Neuvirth suffered an apparent left leg injury Thursday against the Florida Panthers.

If neither Vokoun nor Neuvirth are ready, the Capitals’ net will belong to Holtby as they attempt to halt a string of early postseason exits. Based on how he’s playing at the moment, that might not be a bad thing for the Capitals.

Although Holtby did not face many quality scoring chances against the Rangers, the 22-year-old was there with a blocker, glove or pad when needed. In fact, he made at least one critical save in each period to prevent the Rangers from gathering any momentum.

In the first period, it was pad save on 40-goal scorer Marian Gaborik that preserved the Capitals’ 2-0 lead. In the second, the young netminder made one-on-one stop against Gaborik (six shots) to send the visitors into the intermission ahead 4-1.

That’s as close as the Rangers would get thanks to more heroics from Holtby in the third period. Holtby stopped Carl Hagelin on a short-handed breakaway with a slick stick save near the midway point. Then, only seconds later, he thwarted a second short-handed opportunity when he charged out to the hash marks and poke-checked Brandon Prust.

“That’s one of my mentalities — to be aggressive in those types of situations,” Holtby said of the play on Prust. “It’s a tough situation for a goalie when the puck is just sitting there and he’s skating toward it. He can take a quick shot or you won’t get a good read on it. Luckily [defenseman Dennis Wideman] was there to save the day.”

The win was Holtby’s fourth victory in seven games this season. But this was unquestionably his biggest triumph in a season that began with him getting bumped to third on the depth chart and included a slow start with the minor league Hershey Bears.

Asked if that’s why he had a roller coaster painted on his mask, Holtby shook his head and cracked, “But it kind of ended up being [symbolic] of it.”