Four games and 10 days retrain for the Washington Diplomats this season. They have been eliminated from the playoffs. They have fired a coach.

The Diplomats are playing out the string of what has been their most disappointing year. Tonight, Washington can wipe out some of the bad memories when it journeys to East Rutherford, N.J., to take on The Cosmos in a North American Soccer League game. Formerly from New York, the Cosmos took their superstar-loaded franchise across the Hudson River to play in Giants Stadium at the beginning of this season.

Game time is 7 p.m. and the game will be televised (WTTGTV-5) on a delayed broadcast beginning at 8.

The last time the Dips (9-13, 61 points) faced The Cosmos (13-10, 121), the Pele-led bunch eliminated Washington, 2-0, in a first-round playoff game last year. The Brazilian Black Pearl is now 37 and has slowed considerably but is surrounded by enough other stars to make George Steinbrenner blush.

The Cosmos have Germany's 1974 World Cup captain, Franz Beckenbauer, flamboyant scorer Giorgio Chinaglia (11 goals six assists), highly regarded goalie Shep Messing and Brazil's 1970 World Cup captain, Carlos Alberto.

The potent Cosmos have scored 48 goals compared to only 27 for the Dips. The Cosmos have won six consecutive home games while averaging 33,024 fans per game. They have already broken the league mark for season home attendance and drew more than 62,000 for one contest.

But the playoff-bound club also has problems.Earlier this month, the Cosmos replaced coach Gordon Bradley with former Tampa Bay coach Eddie Frimani.

Immediately there were cries of tampering around the league, most notably from Tampa Bay. Few people believe that Firmani's resignation June 3 as coach of the Rowdies was merely for "personal reasons" as he claimed.

Further credence was lent to the tampering theory when it was learned that The Cosmos had made a cash settlement with Tampa Bay, including an agreement to play an exhibition, with the Rowdies taking the entire gate.

Since Firmani became coach July 7, The Cosmos have won one of three games and have dropped out of the Eastern Division lead. Fort Lauderdale (17-6, 142), has a comfortable lead on both The Cosmos and the Rowdies (13-10, 121).

Washington has surrendered seven goals in the last two games and will be missing sweeper back Jim Steele, woh must sit out a one-game suspension after picking up his 18th penalty card.