If the New York Islanders defeat the Philadelphia Flyers here Thursday night, they will become the first team in National Hockey League history to finish as low as fifth during the regular season and win the Stanley Cup.

Some extenuating circumstances cloud that statistic. For one thing, the Islanders were fifth in a 21-team league; when Toronto captured the Cup in 1949, after finishing fourth, the NHL consisted of only six teams.

More pertinent, the Islanders were not really that bad, considering the caliber of players on their roster. The chief reason they finished fifth was best defenseman in three of the past four seasons, was able to play only 31 of the 80 games.

Potvin suffered a bruised collarbone prior to the season and missed the first eight games. He scored four goals and 21 assists in the next 13 games, then was forced out again with torn ligaments in his right thumb.

This second injury required surgery and Potvin spent three months in the stands, watching the Islanders stumble. It was not until the last week that they were assured of finishing in the top eight and gaining home-ice advantage in the first round of the playoffs.

By that final week, Potvin was back in the lineup. He played the last 18 games and the Islanders' record was 10-3-5. They were unbeaten in the last 12 games of the regular season, following a 3-1 lost at Washington March 9.

New York has won 14 of 19 playoff games, mocking the home-ice statistics by winning two of two in Los Angeles, three of three in Boston, two of three in Buffalo and one of two here. They have almost proven, after finishing 25 points behind Philadelphia, that the regular season is virtually meaningless.

The Islanders amplified that fact a year ago, in an opposite vein. After sweating all season to finish first, accomplishing that feat on the final day of the season, they were ousted in the semifinals by the fifth-place New York Rangers. The "choke" tag was cruelly pinned on the Islanders and it is something they are anxious to discard, preferably Thursday.

"We don't want anything like that defeat by the Rangers to happen again," said the bearded, smiling Potvin. "I think about that almost every time we play."

Potvin had a lot of time to think during his three-month session with that painful thumb. That is not something he wants to experience again, either. He stayed away from the dressing room, because he did not want to be placed in the position of offering advice to a struggling team.

"Really, what could I do?" Potvin asked. "I didn't say anything -- no preaching, no lectures. All I wanted when i came back was to show them some kind of confidence. I think we turned it all around because people started to show confidence in themselves.

"I can remember, year in and year out, I'd be crying for a rest, a few days off to break up that long season. But I didn't want several months. It was a testy period in my life. I still don't know how I managed to keep my sanity."

Bob Bourne, like Potvin, a candidate for the Conn Smythe Trophy as playoff MVP, said of the Islanders' captain, "I don't think anyone in this room recognized what it was like for Denis. He didn't talk to any of us.Most of the time he never came to practice. We'd go days at a time without seeing him. It hurt him and it hurt us."

It took a while for Potvin to regain top form, although his mere presence was enough to get the team moving. Actually, it was not until this final series that Potvin has reached a peak, which could not have been better timing.

Potvin scored two goals in the vital first-game victory over Philadelphia, including the winner in overtime. Then, in game three, when the Islanders established their dominance, he netted two more. Even more important, he has been a defensive standout.

"He's hitting people now," said Islander General Manager Bill Torrey. "I don't think Denis realizes what a devastating effect he has on the other team when he's playing well in his own end and checking hard. Denis is our best defenseman, the best defenseman in the whole league."

There will be no Norris Trophy for best defenseman on Potvin's mantle this year, but what once looked like the worst year of his life is turning into the most fulfilling.

"The cup is everything now," Potvin said. "I've won other awards, but right now the cup is all that's left. We have to win one more. It's so close now."