Rangers center Matt Rempe is congratulated by teammates after his...

Rangers center Matt Rempe is congratulated by teammates after his goal against the Capitals during Game 1 of their Stanley Cup Playoffs first-round series at Madison Square Garden on Sunday. Credit: Kathleen Malone-Van Dyke

The story of Rangers rookie Matt Rempe has been a straight-up fairy tale. And the latest chapter Sunday might have been the coolest yet.

Rempe, the 6-7 rookie forward, scored the first goal of the playoffs for the Rangers on Sunday. It sparked a three-goal outburst in a 2-minute, 6-second span of the second period and a 4-1 win over the Washington Capitals in Game 1 of their first-round playoff series at Madison Square Garden.

And the best part about it was that Rempe’s mother was in the building, watching her son play at the Garden for the very first time. You can’t make this stuff up.

“It was really special because she got to hear the chants and I got a goal and stuff,’’ Rempe said. “Obviously, I love her so much. She’s my biggest fan. We went out for dinner last night and walked around. She’s never really been in New York, so we were just walking around, and it was definitely cool. I bet she was pretty emotional today .  .  . Yeah, she’s the best.’’

How do you not love this kid?

The Garden fans certainly do. They probably cheered the loudest for him on Sunday, and there’s a buzz whenever he steps on the ice. They roar when he checks someone and they chant his name — “Rempe! Rempe!’’ — just because, at times. When he scored his goal, at 4:17 of the second period, the building almost exploded with noise.

“It was a pretty tight [and scoreless] first period,’’ Rangers coach Peter Laviolette said. “And that was a big goal to put energy in the building. Maybe because it was him, too, it put a little more extra juice in the building. And then to be able to get another one right after that [from Artemi Panarin]. So that was a turning point in the game.’’

Panarin scored at 4:50, 33 seconds after Rempe, to make it 2-0. Then Rempe’s linemate, Jimmy Vesey, scored off a faceoff at 6:23 of the period to make it 3-0. It was almost as though a playoff goal from Rempe was worth three times what one from anyone else is worth.

Rempe, who was the first Ranger to score in his first playoff game since North Bellmore native Matt Gilroy did it in 2011, also might have gotten inside the heads of the Capitals, who were angry that on Vesey’s goal, Rempe bumped Washington forward Beck Malenstyn after Barclay Goodrow won a faceoff back to Vesey. The collision knocked Malenstyn down and prevented him from being able to get out to Vesey, which allowed him to get the shot off. The shot deflected off Washington defenseman John Carlson’s stick and got past goaltender Charlie Lindgren.

When asked about it, Rempe had a “who, me?’’ reaction.

“You’re anticipating a [faceoff] loss, so I’m trying to jump through,’’ he said. “And then when he won it back, I want to get a pick, and then I don’t really know what happened. Just, the next thing you know, Jimmy scored, so I was happy Jim scored.’’

Well, the Capitals weren’t. And they were ornery the rest of the game.

Tom Wilson, who is Public Enemy No. 1 around the Garden because of his body slam of Panarin in a regular-season game here three years ago, hit Mika Zibanejad, knocking him to the ice, a couple of times in the second period.

And at the end of the period, when a commotion started in the middle of the ice between Washington defenseman Trevor van Riemsdyk and Rangers forward Will Cuylle, Wilson came over to help and looked right at Rempe. But cooler heads prevailed.

In the third period, Rempe collected a puck in his own end, drove up the ice and fired a shot that Lindgren saved. Washington defenseman Dylan McIlrath bumped into Rempe, who just backed away. With a 3-1 lead, he wasn’t about to give the Capitals anything to get them fired up.

“I was going to the net and he bumped me,’’ Rempe said. “There’s absolutely nothing there, you know. He’s playing hard, I’m playing hard.’’

Someone asked Rempe if he thought he might have gotten inside the Capitals’ heads after his performance.

“I don’t know. I just, I’m gonna play hard,’’ he said. “I feel like if that happens . . . that’s good. That means I’m doing my job. But I don’t know, it’s one game . . . I think I was being effective tonight, but I’ve still got a lot of work to do.’’

What is left for him to do, though?

He’s already become a fan favorite, a folk hero. For a guy who averaged 5:38 of ice time during the regular season (he played 8:33 Sunday), he became a factor in his first career playoff game. And he could be a factor for the rest of the series.

“I know my game,’’ Rempe said. “I can skate well, be physical. I’m built for the playoffs, I think. I think I can play real hard and be a pain to play against, and down low, protecting pucks and then going to the net.

“Yeah, I think I’m built for the playoffs. I think that’s where you want to play, and I was happy how tonight went.’’

So was everyone else — except the Capitals.