The rich New York Islanders got richer and the poor Washington Capitals got poorer yesterday.

A sellout crowd of of 18,130 at Capital Centre saw the Islanders come from behind on third-period goals by Stefan Persson and Mike Bossy to beat Washington, 5-4, and climb into first place in the National Hockey League.

The Islanders matched an NHL record by winning their eighth straight road contest. They are unbeaten in their last 13 games and regained first place from St. Louis for the first time since Valentine's Day, matching the Blues' 104 points and boasting one more victory.

The Capitals are winless in their last six home games and continued an improbable statistic of having won only once -- over Toronto in 1977 -- during the 17 occasions on which a full house exerted the Centre boxoffice crew. More important, Washington is still 17th, one point behind Toronto, with only three games to play.

"I've given up even guessing what we have to have," said Washington Coach Gary Green. "We need three wins, that's the only sure way. Who knows what the other teams will do?"

Three straight victories would not be enough if Toronto, Edmonton and the New York Rangers won all their remaining games, however. The Capitals are in trouble and they know it.

"That was a big game," said defenseman Darren Veitch afterward, his face flushed and angry. "I think every guy in this room is upset right now."

A 35-foot power-play drive by Ryan Walter at 5:20 of the third period lifted the Capitals into their only lead of the contest, at 4-3. The play was set up by Bengt Gustafsson, who wheeled across the Islander blueline through considerable traffic and passed tot he Capitals' captain.

Less than four minutes later, New York pulled even, also in an extra-man situation, as Persson's drive from the left point flipped into the net off the stick of goalie Mike Palmateer, while Veitch wrestled with Islander Bob Bourne just outside the crease.

"We were blocking the edge of the crease and Palmy couldn't come out," Veitch said. "He just didn't have enough room."

The man in the penalty box was defenseman Pat Ribble, sent off for slashing on one of several marginal calls by referee Bryan Lewis.

"I slashed him, said Ribble, nursing a charley horse in his left thigh. "But I just wanted to take his mind off things, it wasn't a full two-hander. And considering some of the calls he wasn't making, I thought that was a pretty bad one."

Bossy's 68th goal won it for New York with 5:28 remaining. Bryan Trottier skated back and forth behind the Washington net, while Veitch fell down pursuing him, and then passed out to Bossy for a close-range score.

"You can't give Bossy that four or five feet," Green said. "It was inexperience. Tags (Veitch's partner, Jim McTaggart) was hanging onto the post."

The Capitals had a lot of inexperience on the backline -- three rookies among five -- during the last two periods because Paul MacKinnon, making his first appearence since he tore up his right knee Oct. 30, was ejected late in the first period as the thrid man in a fight between Palmateer and the Islander's Garry Howatt.

Howatt invaded the Washington crease and Palmateer swung his stick at him. Howatt then charged into Palmateer and MacKinnon promptly knocked him into the net. Although the rest of the scuffle was relatively minor, everybody on the ice received a misconduct for dropping sticks and gloves. That included Bossy, Trottier and the Capitals' Rick Green and Dennis Maruk.

After Bossy's goal, the Capitals had little opportunity to pull even, as the Islanders controlled the puck. Washington did not lift Palmateer for a sixth skater until the last nine seconds, although the puck was in the New York end without a whistle with 30 seconds left.

"I was hoping we'd get a faceoff down deep," Gary Green said. "I'd rather take my chances on an organized situation rather than a scramble at the end."

Clark Gillies was key figure for New York, scoring two goals and cross-checking Dennis Ververgaert out of the decisive play to make Bossy's winning goal that much easier.

Gustafsson netted his first goal in 15 games after a Rolf Edberg steal to tie the game at 1-1 in the first period. After a short-handed scroe by Trottier and Gillies' second goal had built a 3-1 New York lead, the Capitals struck back.

Mike Gartner, another charley horse victim, netted his 47th goal to make it 3-2 and that time the Islanders were doing the shouting at Lewis, because Walter was occupying the crease when Gartner scored. Nevertheless, it extended to 16 games Gartner's club-record point-scoring streak. Only Hartford's Mike Rogers has a longer string this year, 18 games, although Guy Lafleur's NHL mark of 28 is beyond reach.

Edberg, a standout all afternoon, picked off a Persson pass to create the tie. After Persson blocked Edberg's initial shot, Ververgaert kicked the puck back out and Edberg steered it between the legs of goalie Roland Melanson.

Walter's goal threatened Melanson's unbeaten NHL record, but the 20-year-old rookie eventually boosted his mark to 7-0-1.

Green praised his charges' effort in a losing cause, but having been a witness to the Islanders' sluggish 4-4 tie with Pittsburgh at Nassau Colliseum Saturday, he professed to not understanding one thing.

"It disturbs me somewhat to see the way the Islanders played out there today, compared to yesterday," Green said. "They didn't play well at all against Pittsburgh, but we seem to run into teams that are ready to play."

The Capitals had better be ready this week.