The Washington Diplomats overwhelmed the mistake-prone Tampa Bay Rowdies last night, earning a 4-1 victory at soggy RFK Stadium. It was Washington's fifth straight win of the NASL season.

The Dips' third straight triumph at home improved their record to 5-1 going into Sunday's game in East Rutherford, N.J., against the Eastern Division-leading Cosmos, who also won last night.

Diplomat defender Malcolm Waldron scored the winning goal at 31:54 on a direct free kick from 24 yards out, making it 2-1. Tampa Bay's 39-year-old goalkeeper, Kevin (The Cat) Keelan, didn't make a move until the ball was in the net. It was Waldron's fourth goal of the season -- three from direct free kicks -- and third game-winner.

The Diplomat midfield again controlled the game, constantly getting itself or the Washington forwards in position to score. If not for several missed open shots, the score might well have been 8-1.

"We played the game as it should be played," said midfielder David Bradford: "dominating the midfield."

"The midfield was excellent tonight," agreed captain Peter Baralic, who scored the Dips' fourth goal. "We scored four goals against a very good team. We wanted this game badly going into Sunday's game against the Cosmos."

While impressed with the Diplomats' performance, Tampa Bay Coach Gordon Jago faulted his team. "We made some very bad defensive mistakes and were ruthlessly punished for them," he said. "Our performance tonight left a lot to be desired. Washington was more determined than us and it showed."

The rain led to the Diplomats' first goal nearly seven minutes into the game. Ivan Belfiore, who did a marvelous job in marking Tampa's all-star midfielder, Steve Wegerle, kicked a ball that a diving Keelan stopped.

But the wet ball slipped out of Keelan's hands and into an unprotected area of the goal mouth. Keelan, substituting for injured regular keeper Winston DuBose, crawled toward the ball, but Diplomat forward Trevor Hebberd, with a perfect baseball slide in the sopping grass, pushed the ball in with his right foot a split second before Keeland could get there, giving Washington a 1-0 lead.

The Rowdies (2-5) tied it at 25:15 on Frank Worthington's unassisted goal, the ball slipping off Dip goalie Jim Brown's hands and into the net. Jan van der Veen started the play with a free kick that was stopped in front of Brown but bounced off three or four bodies before landing in front of Worthington.

It was the first score at home against the Dips in three games this season and seemed to stir the 5,825 fans.

Only six minutes later, Tampa Bay midfielder Wes McLeod tripped Baralic to set up Waldron's goal. The British defender's incredibly hard kick went between two flinching Tampa defenders and high into the net past a frustrated Keelan.

Ross Jenkins and Baralic added goals in the first 15 minutes of the second half for the final 4-1 margin. Both goals were helped by lapses in the Tampa Bay defense, allowing the Dip attackers to enter the penalty area relatively unmolested. Both were also set up in the midfield by David McGill and Heinz Wirtz.

The Dips have scored eight goals in Wirtz's two games with the team.

The Diplomats dressed quickly and left at 11 p.m. for a suburban hotel, where they stayed last night before taking the train to New York for the first-place battle with the Cosmos.

"I've been thinking about the Cosmos all week," said Diplomat Coach Ken Furphy.

When asked to compare the Cosmos and Diplomats, Jago, whose team has lost to both in the last week, said, "Washington's a much stronger, more physical team. They have very strong runners and don't give you any room. Just call them hard working."