Islanders head coach Barry Trotz, shown here during Game 2...

Islanders head coach Barry Trotz, shown here during Game 2 of the Eastern Conference quarterfinals against Pittsburgh on Friday, April 12, 2019 at NYCB Live's Nassau Coliseum, is wary of assumptions about momentum in the postseason. Credit: Newsday/William Perlman

First the Islanders made the playoffs, thus extending their stay at NYCB Live’s Nassau Coliseum longer than most of the hockey world expected.

Now they might have ended their Coliseum season sooner than most of the hockey world expected — in the best way possible.

Friday night’s 3-1 victory in Game 2 left open the possibility of a sweep of the Penguins, which would mean their next home game would be in the second round at Barclays Center in Brooklyn.

To be clear, that is not the way to bet, not against an opponent this formidable. But the very fact that such a thing can be pondered illustrates the latest improbable turn in an improbable season.

Their 2-0 series lead is their first since 1983, before any player who dressed for them Friday night was born.

“It’s probably a little bit more the script that’s been handed to us throughout the year,” captain Anders Lee said of the us-against-the-expectations narrative, acknowledging the Penguins’ more impressive resume. “This room is a strong room, a close room and one that sticks together, and I think we’re showing that out there on the ice.”

Coach Barry Trotz spoke before the game about the unimportance of momentum in the playoffs, calling its impact “zero. Zero-point-zero, if there’s anything less than zero. Every game is its own entity. Once it’s over, you don’t look back. You have to look forward.”

If that is the case, perhaps the Islanders are just the better team at the moment, with no need for a carry-over from their 4-3 overtime victory in Game 1.

They were even better in Game 2 in that they did not repeat the mistake they made in the second period of Game 1, getting into a wide-open skate-a-thon with the Penguins.

This time the game was gritty and grimy from the start, full of scraps and the ongoing frustration of Pittsburgh’s top line, centered by Sidney Crosby.

Through two games, Jake Guentzel, Crosby and Bryan Rust have totaled eight shots on goal and no goals.

Cal Clutterbuck, whose fourth line often matched up against Crosby’s, said: “You want to make him go through people. He’s probably the best player in the world offensively and he’s hard to contain.

Just try to keep a couple of guys between him and the net and take away his time and space.”

Between games, Trotz preached a take-it-as-it-comes approach, backed up by his vast postseason experience, including a Stanley Cup with the Capitals only 10 months ago.

How often does he bring up his Cup run, and how often do his players ask him about it?

“I always say, ‘This is what I’ve experienced, this is what I can tell you, and this is what’s going to happen,’ just through experience,” he said. “They listen, but you have to live it.

“This is no different than your parents saying, ‘Don’t touch the stove’ when you’re young. You keep touching the stove and then you burn yourself and they go ‘I told you so.’ They’re very good at listening and comprehending, but you still have to live it. You’ve got to do it.”

Doing it they are. Perhaps the fun has just begun.

After Game 1, Trotz gently chided the Coliseum fans, who mostly were raucous, for getting quiet while the Penguins revved up their offense in the second period.

On Friday, he said: “They were good. They get an A-plus from me tonight.”

He took note of the noise from fans still cheering outside the interview room.

“Fantastic,” he said. “That’s what the playoffs are about. What I remember about this building [as an opposing coach] is it’s a hard place to play and the fans are fabulous and passionate and they’re pushing you along.”

But did they do such a good job of it that they helped push the Coliseum out of the hockey business until next season?

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