Four days before their most important game of the year -- a game labeled by management as one that could make the franchise -- the Washington Diplomats yesterday talked about a rapidly growing problem on the team: a loss of confidence.

"We're losing our games in the second half because we have no belief in ourselves, " said defender Bob Iarusci. "We don't feel we can win. We've got no self-confidence at all."

Five of the Diplomats' six losses have been by one goal, two in shootouts. In three of those six losses, the team led at halftime. The Cosmos, Sunday's opponent, have built much of their reputation as the NASL's top club because of their ability to win the close game. Iarusci, who played on the Cosmo's Soccer Bowl championship teams in 1977 and 1978, believes confidence is the difference between the two teams.

Last year, the Cosmos beat the Diplomats twice in shootouts, coming from 4-1 down the second time.

"They never panic, " said Coach Gordon Bradley. "They just keep plugging away; they never change their game. They know the goals will come and they usually do."

The same cannot be said for the Diplomats. The opportunities have come -- the team is extremely creative at midfield -- but the goals have not. The Dips have found the net only 17 times in nine games.

Striker Bobby Stokes, who has yet to score, said yesterday he feels at least partially responsible for the team's troubles and would not object if Bradley benched him Sunday.

"I'm very disappointed in myself," Stokes said. "If I don't play and the team wins, that good, It's just important right now that we get a win because we need one badly.

"Even though I haven't been scoring, I feel as if I've been contributing in some other ways. We've been in every game but quite a few of us have been lacking confidence out there. Because of that, every game the team has to carry a couple of people.That isn't a good situation."

Most of the players said yesterday that they feel the team has played better the last two weeks, even though the results, 2-1 losses in Fort Lauderdale and Atlanta, do not reflect that improvement.

"A few weeks ago, I would say we were losing because we weren't playing well, Period," said defender Tommy O'Hara. "Now, we're playing better, but still not winning. I don't know what's wrong.

"Losing to Atlanta certainly didn't help us, and going into the Cosmos' game off a loss like that is not good. It doesn't help your frame of mind at all. This game is very important to us. It could help our confidence and everything that goes with it if we win. If we lose, we'll certainly be very, very down. But it won't be the end of the season, either."

Most of the players agreed on one thing: a win Sunday against the 7-2 Cosmos could turn things around in a hurry.

"Last year at this point of the season, we played more together and got along better together," Iarusci added. "We have a lot of new people. We're not playing well as a unit. We need to win to believe in ourselves as a team."

Or, as Stokes put it: "We need a good performance and a good win Sunday.

But if I had to choose, I'd certainly take the win. Any win at all."

Bradley was unsure yesterday what changes, if any, he would make in the lineup for Sunday. Johan Cruyff returned to the doctor to have his thigh reexamined and Bradley said he would make no decision on changes until he is certain Cruyff can play; one possibility: Sonny Askew might return to the lineup with Cruyff moving up front to replace Stokes.