The Washington Diplomats find themselves in an awkward position tonight when they play the defending North American Soccer League champion Cosmos in the regular season finale at RFK Stadium at 8 o'clock.

"Unfortunately, the weight of finishing with the best second place record in the (National) Conference isn't completely on our shoulders," said Dip Coach Gordon Bradley. "We have to depend on others to help us, and you hate to be in a spot like that. Everything is ifs and ifs."

Washington (16-12 and 144 points) hopes of capturing that second place spot and that precious home-field advantage for the one-game first-round playoff game next week were kept alive following Portland's 3-2 loss in Seattle on Monday night.

Portland (19-10 with 158 points) closes out the regular season tonight in Colorado. A victory by the Timbers over an 8-20 Colorado team would sew up the second-place spot regardless of what Washington does in its final games.

"The Portland loss the other night at least gives us a chance to shoot for something. That makes this game against the Cosmos that much more important," said Washington striker Paul Cannell.

Two consecutive losses by Washington also has left the door open for surging Toronto (15-13 and 135) to sneak past the Dips for second place in the Eastern Division.

Should the Dips lose and th Met- ros win tonight in Tampa Bay, the regular season wrapup in Toronto on Sunday would be important for Washington. If the Metros finished ahead of Washington, the Dips would become one of the two wild card entries and probably open the playoffs in Vancouver.

But Washington may catch the Cosmos coasting tonight. With nothing to gain from a victory, the Cosmos may take this opportunity to rest several of their ailing starters.

In last year's finale at RFK, the Cosmos infuriated the Dips' front office and most of 31.283 fans by holding out several of their superstars in a 3-2 Washington victory.

"I wouldn't be surprised if they did agains," said Bradley. "But their subs are almost equal to their front-line players. When you think of players like Seninho and (Giuseppe) Wilson being subs, that should tell you something about their team."

The Cosmos front line includes Giorgio Chinaglia who has established a scoring record with 32 goals and 11 assists for 75 points: Steve hunt (12 goals, 11 assists).

With "Der Kaiser," Franz Beckenbauer and Yugoslavian star Vladislav Bogicevic, each with eight goals and 16 assist, operating from the midfield the Cosmos have scored an astounding 83 goals, 15 more than any other team.

"They beat us 6-1, the first time but they aren't five goals better than us," said Cannell. "We'll play much better this time. And I hope all their players are in there. The win will be more satisfying."