Doug Jarvis' second goal of the game, with 50 seconds left in a five-minute overtime period, carried the Washington Capitals to an emotional 5-4 victory over the New York Islanders tonight.

He followed up a tremendous effort by Gaetan Duchesne, who took the initial shot at goalie Bill Smith, then poked the puck free between Smith's legs.

"It might have gone in anyway, but I wasn't going to wait around to find out," Jarvis said. "It was a big goal -- to win in this building and the way we came out. We didn't want a tie; we wanted to come out on top."

Dave Christian, who also scored twice, tied the game with 6:32 left in regulation by converting Craig Laughlin's pass while Bob Carpenter screened Smith.

By winning for only the third time in 27 regular-season visits to Nassau Coliseum, the Capitals increased their Patrick Division lead to four points over Philadelphia and eight over the Islanders.

There was one unpleasant note, however. Left wing Gary Sampson, who had played so well in recent weeks, suffered indeterminate ligament damage to his left knee when Pat Flatley checked him in the second period.

Washington, although trailing most of the game, controlled the play and had the better chances. The Capitals outshot New York by 40-16, including a 6-1 edge in the overtime. Over the last 44 minutes, the shots were 26-6.

"After outworking them and outshooting them the way we did, it was important to win the game," Coach Bryan Murray said. "If we had lost that one, the guys couldn't have helped being discouraged."

The Islanders had won six in a row from Washington, including four straight in the divisional playoff final in April.

"There was a block of not being able to beat them," Washington captain Rod Langway said. "Maybe now we can turn it around. After the first two periods tonight, we were forcing them at their blueline and putting pressure on their defense. It's got to give them something to think about."

The Capitals had to overcome adversity in this one. The Islanders' goal by Pat LaFontaine that tied the score at 1-1 was bitterly disputed by goalie Pat Riggin, who insisted he had covered the puck before it was completely across the goal line.

John Tonelli's goal that increased the Islanders' lead to 3-1 came on their only shot in the first 18 minutes of the second period. It was tipped in by Langway as he tried to block it.

"Coming back after being down by two goals is a great character builder for us," Langway said. "The breaks went their way a bit, but you can live with that. You can't live with mistakes and the last two nights we haven't made very many."

On Wednesday, the Capitals beat Philadelphia, 6-0, for their first victory in four meetings with the Flyers. Then they flew here, following a two-hour delay because of the snow in New York, and beat the Islanders for the first time in three tries.

The Capitals are unbeaten in extra time. They have played an amazing 10 overtimes in 37 games, winning three and tying 10. The Islanders, once the best in sudden death, suddenly are dying at 1-4-1.

Duchesne's sixth goal in nine games sent Washington out in front, as Smith lost sight of the puck after blocking Langway's shot.

Each team was a man short when LaFontaine took Stefan Persson's headman pass, via Greg Gilbert's deflection that averted a two-line whistle, and beat Riggin on a breakaway.

LaFontaine's backhander spun off the goalie and bounced to the goal line, where Riggin felt he covered it in time. He complained bitterly and still was berating the goal judge at period's end.

"I saw it half in and half out," Riggin said. "When I reached down, I swear it was on the line and it has to be all the way across to count. I don't argue too often, but that was a very important goal. It's tough to keep your composure in that situation."

Before the first period ended, Flatley sent a low wrist shot off Riggin's pad from the slot to give New York a 2-1 lead.

When Langway deflected Tonelli's power-play shot from an acute angle at Riggin's right into the net after 34 seconds of the second period, things looked black for Washington. But New York got only five shots the rest of the way.

"They normally get a lot more quality chances than that," Murray said. "This was a big game and if they were going to make a move on us, tonight was the night to do it. But we held them off."

Jarvis began the comeback by lifting a backhander over Smith after the goalie went down blocking a drive by Larry Murphy.

Darren Veitch, who took a career-high eight shots at Smith, made his offensive mark with a fine pass out of the right-wing corner to Christian in the slot for a game-tying score with one second left on a penalty to Persson.

Smith dived all directions to maintain the tie; once, his birdcage was kicked off by Duchesne. Having applied all that pressure without result, the Capitals had to be deflated when Tomas Jonsson's 40-footer got past a screened Riggin midway through the third period.

But Christian was able to tie it again with his 14th goal.

In case anyone thinks this wasn't a big game for the Islanders, let it be recorded that in the closing minutes of regulation time, they asked for an examination of Bengt Gustafsson's glove. That worked when they pulled it on Carpenter in the playoffs. Not tonight.

In other games, the New Jersey Devils took fifth place in the Patrick Division from the New York Rangers by beating the Toronto Maple Leafs, 4-1, in East Rutherford, N.J.; in Quebec, Mario Tremblay scored twice to enable the Montreal Canadiens to beat the Nordiques, 5-3; and in Inglewood, Calif., the Boston Bruins scored four goals -- two by Steve Kasper -- in the third period, then played to a 6-6 tie with the Los Angeles Kings.