They walked off the ice after what was possibly their last practice of the season, relaxed and smiling. The New York Islanders, on the verge of drinking from their fourth straight Stanley Cup, are poised and eager to dispose of the Edmonton Oilers in Tuesday night's game for a four-game final series sweep.

In contrast, the Oilers filed into Nassau Coliseum looking as grim as the task ahead of them: winning one game to stay in contention for the Stanley Cup, winning three more to snatch it from the defending champions.

"We've been there before," Islanders captain Denis Potvin reminded listeners today. "It's not being decided between two teams that haven't been there before. This isn't a series between Boston and Edmonton, as some people have predicted all year long. It's us. We've had the Cup, and that makes it that much harder for another team to take away."

Through the first three games of the series, the Islanders have kept Wayne Gretzky without a goal. He has had chances, but superior goaltending by Billy Smith and the Islanders defense have nullified his opportunities.

"It's not as if we're concentrating only on Gretzky," said center Butch Goring, who, along with Bryan Trottier, shifts into the slot area for added insurance in covering the Edmonton wingers. "We are just playing basic hockey, and whoever's closest to him (Gretzky) takes him out."

Goring said he and his teammates had anticipated the Oilers playing exactly as they have, "which is well, but they're not used to playing a team that checks the way we do. People expect Gretzky to freewheel, the way he has all year. But maybe he can do that against all those western teams. They don't play enough clubs like the Islanders, and obviously it's hurting them now. They're not sure how to get something going."

Edmonton Coach Glen Sather said his team will skate Tuesday night just as it did on Saturday night. "This hockey club has never quit," he said. "The Islanders may be great, but we're certainly not going to lie back and wait for them to come at us."

At today's NHL awards luncheon, Sather stood at the dais and invited his team to stand and drink a toast because they had gotten this far. He also asked the Islanders to toast themselves "because you're such a great team." Sather's angry outbursts over slashing incidents by goalie Smith during Games 1 and 2 in Edmonton apparently had been spent.