The Diplomats couldn't restrain their joy after dominating 1980 Soccer Bowl finalist Fort Lauderdale last night at RFK Stadium, winning, 1-0, on David McGill's splendid header at 47:22.

They talked of teamwork, of how a squad of modestly talented men could completely outplay a Striker team that has stockpiled world-class players.

They talked of how right fullback Benny Dargle stopped Fort Lauderdale's relentless midfielder. Teofilo Cubillas. The Dips talked about how their midfield controlled play the last 87 minutes; how Coach Ken Furphy's intense midweek practices readied them to win their thrid straight and to avenge a 2-1 loss to these Strikers in Fort Lauderdale three weeks ago.

Sharing the joy were 9,212 fans.

The first professional score for the 20-year-old McGill was a thing of beauty.

Ivan Belfiore, making his first start after pulling a hamstring in preseason, passed to Trevor Hebberd in the near corner. Hebberd, whose goal earlier was nullified because of offsides, looped a crossing pass toward the Striker goal.

McGill was standing 15 yards out to the right of the goal. He leaped off his right foot and bumped the ball off his forehead to the right of Fort Lauderdale goalkeeper Jan van Beveren.

"I just ran into the space in front of their keeper and jumped toward the ball," McGill said. "I've got good jumping ability. I saw van Beveren in the middle of the net, with the other side wide open. Their sweeper was out of position so I was open."

"We don't have any stars," goalie Jim Brown said. "We all work hard. Fort Lauderdale's got the big names. But that didn't mean anything tonight, did it?

"They're world-class players and we're no-names. But we did a great job," Brown said, not bragging, but in admiration of a near-flawless Diplomat performance. "Just a great job."

After the opening three minutes, when Fort Lauderdale tried to overwhelm the Dips with offensive firepower, Washington pinned the Strikers back in their own zone and worked over the visitors. The Dips outshot the Strikers, 19-9, forcing van Beveren to make six saves.

Fort Lauderdale didn't get off a shot in the second half until 11 minutes remained. And that weak squib, by Robert Moschbach, hardly threatened the Dips' lead.

Cubillas, who had scored four goals in the Strikers' first three games, got off only one shot. That was a direct kick early in the game that sailed past Brown but shot off the crossbar and right goalpost.

Gerd Mueller, the stalking striker, also had only one shot. There was one shot for lightning-fast Elia Figueroa. And none for Ray Hudson, who left at 39:35 with a twisted left knee.

Striker Coach Eckhard Krautzaun said when Hudson, his best player, was injured, "Our game plan was destroyed." With Hudson out, Dargle's ability to stop Cubillas became the focal point of the game.

"Coach Furphy devised a plan forme to mark Cubillas," Dargle explained. "If you stop Cubillas, you stop Fort Lauderdale, especially on the road. I'm a bit quicker than he is, which means I can take chances going for a close ball. I kept him facing his own goal most of the night. I just didn't let im turn on me."

McGill's goal thrust him into the limelight for one of the few times in his short career. After getting cut from Vancouver before the 1980 season, McGill, a 20-year-old defensive midfielder, called every coach in the league before catching Furphy in his Detroit Express office a year ago.

Furphy told McGill the team would pay for his trip from British Columbia only if he made the team.

"I said to myself, 'I know I'm good enough, I just need a chance to show what I am capable of,'", McGill said. "The first five games of last year, I didn't play. But I played in every one of the next 25."

Said Furphy: "He took that header very cooly, didn't he? Such a young fellow too."