Okay, it was April Fool's Day. But the Washington Capitals really beat the New York Islanders. Honest.

Building a 6-1 lead in the first two periods, the Capitals wound up 6-4 winners for their first-ever success against one of the two best teams in the National Hockey League.

This was no coasting team caught flat, either. It was a tremendously important game for the Islanders, who are trying to beat out Montreal for the overall points title and home-ice advantage in a prospective Stanley Cup final matchup.

But it was most important to some of the Capitals, too, notably team captain Guy Charron, who called a special morning meeting of the Players without Coach Danny Belisle.

"It was important for us to do something in the next four games and the guys discussed a lot of things," Charron said. "We've had key players injured, but we can't quit. That gives the opportunity for other guys to perform. We may have guys hurt next year when we're fighting for the play-offs. I'm sure everybody feels good about the whole thing now. We were mentally ready."

"We wanted to start right now to get moving next season, if we're going to be a success," said goalie Jim Bedard, a sensational performer as he stopped 32 New York shots. "We've been kind of lifeless the last few games. So we tried to air a few things we had to do to end on a positive note."

In 19 previous meetins with the Islanders, the Capitals could recall 16 losses and three ties. They were out-scored 86-27 and at Capital Centre the goal-scoring figures read 39-8 with five shutouts in nine games. Washington never had scored more than three times in a game against the Islanders, so in two periods, the Capitals were dougbling any previous pleasure for their loyal fans.

Three of those goals came in the first 10 minutes and provided Islander goalie Bill Smith with an early shower. Dennis Maruk achieved the 30-goal mark for the third time in his four-year NHL career while the Capitals were shorthanded, Leif Svensson deflecting Mike Kaszycki's attempted pass from the corner to Maruk in the slot.

Yvon Labre picked off and errant Bryan Trottier pass just inside the blue line and unchallenged, weaved his way close enough to beat Smith with a 30-footer for his first goal.

Then Robert Picard produced the first of three Washington power-play scores, netting his 21st goal after collecting Ryan Walter's pass through the slot.

Picard was not around for the Islanders' third-period charge, departing early in that session with a bruised-possibly separated-left shoulder after Bob Nystrom caught him off balance following a slap shot.

Rolf Edberg sandwiched two goals around Mike Bossy's 62nd in the second period for a 5-1 Washington lead. Edberg had hit a post shortly before he beat Bob Lorimer to rebound and knocked it past relief goalie Chico Resch. Then, after Bossy snapped the shutout, Edberg scored on a rebound of a Maruk breakaway for his 12th goal.

Then it was Charron's turn to practice what he preached. With only four seconds remaining in the period, he connected on a rebound of a Picard shot to become the first player to score 100 goals in a Washington uniform.

After Picard departed, holding his left arm, the Islanders poured on the power. Clark Gillies, Kaszycki and Bossy trimmed the margin down to 6-4 and the awful possibility existed that the Capitals, who had blown so many leads late in the game, would make this the all-time blooper.

It didn't happen, although Resch was yanked for a sixth skater with 110 seconds left and the puck remained in the Capitals' end for the first 102 of those ticks of the clock. Bedard made one super save, on a shot by Stefan Persson, and his teammates managed to keep the puck at least a few feet from trouble the rest of the time.

"They really kept me hopping," said Bedard, whose postgame clinch with compatriot Gary Inness brought joy to many long-suffering Capital watchers. "They work the puck so well from behind the net. But I think tonight we wanted it more than they did."

Bossy's 63 goals set an NHL record for a right wing, wiping out Reg Leach's three-year-old mark of 61. Trottier's three assists gave hime 126 points and strengthened his hold on the scoring lead. But the important numbers for the Islanders were the three points they fell behind Montreal.

Had they won, the Islanders would have been one point back and, with a game in hand, could have beaten out the Canadiens by winning their four remaining games. Now, they must bope that Montreal stumbles. It is not a bright hope and Resch, unhappy at the way the Capitals knocked his teammates around, sounded a warning.

"We're going to be in trouble," Resch said. "We're the toughest team in the league, but if we don't go out and prove it, any team will take advantage of us. We knew Washington was going to beat us sometime, but I certainly didn't think it was going to happen tonight."

One person who didn't mind looking foolish, in accord with the calendar, was Belile, who had said Saturday, after Boston extended the Capitals' winless string to 10, that his team couldn't play any better.

"This was our best effort collectively as a team-everybody was just super," Belisle said. "We started the tempo right off the bat. Everybody was humping and, hwerever the puck was, there were white shirts around it. The Islanders you could see on those first four or five shifts couldn't believe it. They didn't expect this and they couldn't get untracked."

The Capitals have three games left and, particulary if Picard is unable to play, they could lose them all. But this one great effort has guaranteed a positive outlook for the players to get through the summer.

"It's great to play against the best teams," said defenseman Rick Green, whose body was an effective force in the Washington end. "If you want to be the best, you have to beat the best. Now we know we can do it."