The New York Islanders practiced yesterday at Nassau Coliseum. That, in itself, shows the dedication of this remarkable team, which now must be considered an odds-on favorite to win a third straight Stanley Cup.

In the previous 13 nights, the Islanders had played nine games, most of them tense, exciting contests that would have left many players feeling drained. They played four games in five nights against Pittsburgh before winning that first-round series in an overtime finale. Then it was four in five against the New York Rangers, winning three in a row after an opening loss.

Most teams scan the preliminary draft of the relatively meaningless regular-season schedule to avoid demanding four-in-five situations, but in the first two rounds of the most meaningful playoffs they are routine, because of the phobia of some NHL officials who fear criticism should the Stanley Cup be decided in June.

Tonight at Nassau Coliseum the Islanders can eliminate the Rangers and advance to the Stanley Cup semifinals. More important to some of the weary wearers of orange and blue, they probably will be able to rest for a day or two.

"It doesn't bother me as much when we win," said Denis Potvin, 28, after the Islanders pulled out a 5-3 victory over the Rangers Monday night. "It won't change, unless we can get a few days' break after this series. I just hope Boston and Quebec go the limit."

That is a reasonable possibility. The Adams Division series, which resumes tonight at Boston, is the only one tied after the first four games. In the other best-of-seven divisional finals, Chicago takes a 3-1 lead into St. Louis tonight and Vancouver enjoys a 3-1 margin at home against Los Angeles.

The exigencies of the playoff schedule have almost made Potvin appreciate the proximity of Madison Square Garden, where he is routinely showered with obscenities every time he touches the puck.

"I can't repeat any of the things they yell," Potvin said. "I try to block it out, but sometimes I can't help but hear it. But it doesn't really psych me out.

"I have no complaints about the Garden or New York hotels or anything else," Potvin said. "Thank God we don't have a lot of traveling. Last year, when we played Edmonton in the quarterfinals, it was just awful. We lost the fifth game at home and had to go out there to end it. But when you have to do it, you don't think about the traveling. You just go out to win and get it over as quickly as possible."

The Islanders did a good job in that respect during the past two seasons. They were not forced to the limit of any series in winning two Stanley Cups and it took Pittsburgh this time to create a must-win situation.

So many games in so short a time are tough on players such as Potvin, who are used in special-teams situations as well as extra shifts late in the game. But they can be a blessing to fringe players such as ex-Washington defenseman Gord Lane, who see more action than usual.

"I'm never tired," Lane said. "I'm getting more ice time and it's getting to be more fun. It's a lot of fun, when you play a lot and win a lot."

"It's survival of the fittest and it's atrocious, but you have to play them and we'll play them," said Islander Coach Al Arbour. "We try to use as many players as possible and not wear anybody out."

Quebec and Los Angeles were the only other teams forced to the five-game limit to survive the first round. The Nordiques, after dropping the first two games in Boston, seem to have discovered a second wind, possibly with the return to action of injured Peter Stastny. Boston is struggling, too, with rookie goalie Mike Moffat losing the magic touch and yielding six goals in 40 minutes Monday.

The Kings, however, appear to be showing the effects of that remarkable first-round victory over Edmonton. With two straight one-goal losses on home ice to Vancouver, Los Angeles figures to start its vacation on Thursday.