Islanders 3

Rangers 2

By failing to come to the Garden last night committed to playing 60 minutes against the Islanders, the Rangers made this upcoming final week of the regular season far more difficult for themselves than necessary.

Players keep going down (Marek Malik became the sixth regular out of the lineup when at yesterday’s morning skate he aggravated the shoulder injury that sidelined him for five games early last month), but the magic number for clinching first place in the Atlantic Division and home-ice advantage does not.

Instead of having the opportunity to clinch the Atlantic crown in Pittsburgh tomorrow night, the Rangers have some heavy lifting in front of them. With three games remaining after a 3-2 loss to the Islanders in which the Rangers ho-hummed it for at least half the match, the Blueshirts lead the Flyers, who have a game in hand and whom they visit on Saturday, by three points.

And if the Rangers care to crane their necks for a better look behind them, the Devils, who play the Flyers at the Meadowlands on Thursday and Sunday, are five points back.

There are therefore a lot of scenarios facing the Rangers as they prepare for their first postseason tournament in eight years, and all of a sudden some of them aren’t so good. And oh, by the way, did someone say, “Henrik Lundqvist?”

The Rangers are saying that except for perhaps Martin Rucinsky, all of their injured athletes will be fine for the playoff opener next Friday. Which means Malik, Steve Rucchin, Darius Kasparaitis and Tom Poti. They expect Lundqvist will be able to play, as well, but he’s been down now for five games with a hip-flexor injury that wasn’t supposed to be much of an issue at all, at first.

The Rangers are downplaying The King’s extended absence, with Tom Renney last night again saying the team is being “very, very cautious” with Lundqvist, and no doubt the coach is telling a scout’s-honor truth. At the same time, however, Lundqvist has not only been out longer than anticipated, the goaltender said yesterday he had “regressed a little” rehabbing the injury he apparently sustained in Ottawa on March 30 but did not admit to until two practices later, on April 3.

“I felt a little twinge skating in Boston on Saturday,” said Lundqvist, who has been off the ice since but hopes to face some shots at today’s practice. “I never had an injury like this that kept me off the ice, so I can’t compare this to anything before, but I know my groin is a little bit sore.”

Not that that’s a big deal for a goaltender. Not that a sore elbow is a big deal for a pitcher. Not at all.

We understand we’re getting ahead of ourselves here. The Rangers, however, need to be careful they don’t allow the Flyers or Devils, not to mention both, to get ahead of them. In order to avoid that ignominy, the Rangers will have to play with more effort than they did last night before a furious, 24-shot, two-goal third period made the score respectable.

“We have to go into the playoffs the same way we went into the Olympic break, thinking that no one could beat us,” Petr Sykora said. “We have to get our game back.”

Getting The King back wouldn’t hurt, either.

larry.brooks@nypost.com