While they savored Thursday night's 5-4 overtime victory over the New York Islanders, the Washington Capitals were forced to pay dearly yesterday.

Left wing Gary Sampson incurred a partial tear of the medial collateral ligament in his left knee when he was checked by Islander Pat Flatley, the team learned. The knee will be placed in a cast for two weeks and Sampson will be out from four to six weeks, according to team physician Stephen Haas.

It was a harsh blow, because Sampson had been outstanding in recent games. After starting the season in Binghamton, he came back to get nine goals and 10 assists in 34 games, while posting an excellent plus-16 rating.

"Gary getting hurt is a tough one for us," said team captain Rod Langway. "He and Gaet (Duchesne) are our only natural left wingers and they've both been doing a great job. I know how much Gary means, because I come up the left side and he makes it easy to move the puck up the ice."

Sampson, who is on crutches, accepted the injury philosophically.

"It feels a little better today," Sampson said. "I suppose it could have been worse, but it's tough to take because things had been going so well. He came across and caught me with his knee and twisted me around."

Summoned from Binghamton was left wing Greg Adams, who looked good in an eight-game stretch with Washington this season. He was selected from the Capitals' farmhands -- including AHL scoring leader Lou Franceschetti -- after Genreral Manager David Poile and Coach Bryan Murray watched Binghamton's 4-2 victory over the Skipjacks in Baltimore last night.

Another player under close scrutiny from the Washington brain trust was goaltender Al Jensen. Playing his first game in six weeks, Jensen stopped 32 Baltimore shots.

Bob Mason, the man who benefited from Jensen's forced inactivity, will go after his sixth straight victory tonight when the Capitals face the Hartford Whalers at Capital Centre at 7:30.

Hartford, along with Minnesota and New Jersey, engaged in the bidding war for Mason won by the Capitals after the 1984 Olympics.

With Thursday's victory, Murray has won more than half his NHL games (132-90-41). It will take all his savvy to motivate the Capitals for the meeting with Hartford, after the team played at such a high emotional level in back-to-back victories over Philadelphia and the Islanders.

"Physically we're ready, but mentally we have to prepare," said defenseman Darren Veitch, a standout Thursday. "We have to be ready for every game and we know Hartford will be going all out, because they're fighting for a playoff spot. Considering our last two games, it may be hard, but if we're as good as we think we are, we can do it."

Last night in Pittsburgh, the Whalers drew a blank. Goalie Roberto Romano stopped 34 Hartford shots and the Penguins' 4-0 victory gave them the best 10-game span in their 18 years in the league, 8-2-0.

In other NHL action, Buffalo also won a 4-0 home game, over Winnipeg, a second straight shutout for Sabres goalie Tom Barrasso. He had to stop only 14 shots to run his unscored-on time to 133 minutes 20 seconds. Buffalo is on a 5-1-5 streak.

In Calgary, Lane Lambert's third goal of the game, off a rebound scramble at 14:57 of the last period, broke a tie and gave the Detroit Red Wings a 4-3 victory over the Flames. Philadelphia left winger Lindsay Carson also had a hat trick, his three goals leading the Flyers to a 7-4 victory over the Canucks in Vancouver.