The New York Islanders loyalists, the ones who dress up as Stanley Cups and dedicate banners to every individual on the club, have come to expect, even demand, top-level hockey at this time of year. After three Stanley Cups, even a few off nights in a season are scarcely tolerated.

But tonight, even the pickiest of fans could not fault the Islanders, who played probably their best game of the year in defeating the New York Rangers, 5-0.

"Things are starting to go so well," said Bob Bourne, who set up three goals, including two of three by Duane Sutter. "We were working from the start and we're starting to go."

Tonight the Islanders had to go without Bryan Trottier, who suffered a slight sprain of his left knee Thursday in the first game of this Patrick Division final. But even without Trottier's hustling presence (and minus defenseman Dave Langevin, also injured Thursday), the Islanders needed just 54 seconds to establish the theme for the evening: winning, of course.

John Tonelli's goal, set up on a cross-ice pass from Bob Nystrom, provided the early momentum the Islanders never lost. Sutter followed with two more goals that period, and a third in the next period, after his brother Brent had swelled the lead to 4-0.

It was Sutter's first ever NHL hat trick, but he wasn't dancing for joy in the Islanders' dressing room. "Let me sit down," he said to the media mob that surrounded him. He had not expected to score three goals, no, but said it "was nice to be able to contribute something."

Islanders Coach Al Arbour said he had expected a much better game from the Rangers. "They're a fine skating club and with those weaving patterns, we tried to cut their lanes away from them," he said. "It worked tonight. We need balance offensively, and we've been getting it. You can't rely on just a couple guys through the playoffs."

Arbour refused to act too optimistic in spite of his team's 2-0 lead in the Patrick Division final, which resumes in Madison Square Garden on Sunday and Monday. "They'll probably get down on themselves and we expect them to come back very strong."

Rangers Coach Herb Brooks knows his club will have to do just that. "Ask anybody on this club and they'll tell you the only way we can be successful is to show up for work and work our tails off," he said. "Tonight we ran around and did very little, and that's largely because of the fine play of the Islanders."

Indeed, the Rangers managed only five shots on goal in the first period, six in the second. They were hardly a match for the home club, whose crisp passing game, excellent defense and superior goaltending by Billy Smith, who was superb during a late-game span of 1:27 that the Islanders skated two men down, combined for the kind of hockey that is the Islanders' springtime specialty.

Brooks thought Trottier's absence was "a catalyst, an inspiration."

"How many times have you seen teams whose key player is out and they seem to serve as a source of inspiration?" he said. "When I heard he was scratched, I thought that's what would happen."

Brooks' team, which had begun to settle down a bit in the third period ("By then, it's history," he said) had problems getting its wide-ranging offense moving. The Islanders cut off nearly every opportunity for the other New Yorkers to get back into the game and by the final period, even with no more Islanders scoring, the Rangers had begun to look tired.

By contrast, the Islanders appeared ready for more. "Who could be tired after a game like this?" asked Nystrom. "I bet we could go out and play a a game again. That's the thing about the playoffs; you do well, and it grows and grows and gets better all the time."