Thomas Greiss of the Islanders makes a save during the...

Thomas Greiss of the Islanders makes a save during the first period against Joel Eriksson Ek of the Wild at Barclays Center on Sunday. Credit: Jim McIsaac

If there’s anything that could make a goaltender freak out, or at least become a tad nervous, it would be to lose his stick while the opposition is whirling around the net in the closing minutes of a one-goal game. That is high drama in the crease.

What goes through a fellow’s heart in such a frantic moment?

“Nothing, really,” said Thomas Greiss, who handled that very scenario for the Islanders on Sunday afternoon. “You focus the same way, on the game. You just make your reads and hope for the best and look for a chance to go out and get it.”

No big deal. That would be Greiss’ motto, if only he could work up enough emotional steam to come up with a motto. You get the impression that his expression would be exactly the same if the roof caved in or if someone told him he had just won a $100-million lottery.

“That’s Greisser,” defenseman Johnny Boychuk said, after pointedly not saying a word when asked to encapsulate the goalie. “I can’t really say too much more. That’s his personality.”

Greiss would be a heck of a poker player. In terms of reaction, he gives away almost nothing. He doesn’t give much daylight to shooters, either, which explains a lot.

Quietly, he has been a huge presence for the most surprising team in major-league sports. He does not get the acclaim of fellow Islanders goalie Robin Lehner, whose stellar play has been accompanied by an inspiring story of overcoming addiction, but Greiss has been solid.

On Sunday, he was exceptional when the Islanders needed him most, on the Wild’s power play in the middle of the third period to preserve the Metropolitan Division-leading team’s 2-1 victory at Barclays Center.

He also stood his ground and kept his composure after losing his stick toward the end.

“He’s pretty calm all the time. Winning, losing, he’s just a happy guy,” defenseman Ryan Pulock said. “Obviously, the success he has been having this year has been tremendous. Both of our goalies have been a big part of why we are where we are.”

If you are looking to unlock the mystery of why the Islanders are flawless (9-0-0) in the second halves of back-to-back games, you might want to start with this: They have two excellent goalies who share the load and allow each other to stay sharp. Seven times in those back-to-back situations, Lehner and Greiss each played once (Greiss won on Nov. 23 and 24, Lehner won on Dec. 28 and 29).

It is an especially sticky spot for Greiss, who is not technically the No. 1 guy and thus does not have a predictable rhythm. Still, he has not had a regulation loss in more than a month.

“Greisser’s personality is just really laid-back,” Barry Trotz said. “If I said, ‘Hey, you’re not going to play for the next five games,’ he’d be, ‘OK, I’m fine, I’ll be ready.’ If I said, `You’re playing tomorrow,’ he’d be, `Yep, I’ll be ready.’ What I like about him is, it’s whatever is best for the team. He has no agenda. That is endearing to his teammates, to everybody.”

Teammates say Greiss was just as serene last season, when he went nearly a month without a win while many people blamed him for the team’s troubles.

“It’s just my mentality, I guess,” Greiss said after a 26-save effort Sunday improved his record to 16-8-2, his goals-against average to 2.28 and his save percentage to .927. “I’ve calmed down a little with age, but I was always kind of a calm guy. Not too crazy.”

He never asked for thanks or even revealed who he was three winters ago when, during a blizzard that postponed a game, he bought a tow rope at Home Depot and freed four Long Island motorists from snowbanks. Four big saves, no big deal.

“He cracks a smile once in a while, but that’s about it,” Pulock said, smiling at the thought of it. “He doesn’t get too worked up over anything.”

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