SOCCER IS a fast-moving game -- and, sad to say, is fast moving out of Washington, barring a sudden turn of events. Unless something dramatic happens by noon tomorrow, the Washington Diplomats will cease to exist. That is the deadline set by the North American Soccer League for a buyer to take over the team from the Madison Square Corp., which wants out -- fast. But the Dips should not, and need not, be left to vanish this way. The league should call a timeout and give Washington a fair chance to save its team.

Neither a deadline extension from the league nor the recruitment of a new group of investors is impossible. On the contrary, it would be foolish on all counts -- from sound business to civic pride -- for the league to hold stubbornly to the Monday execution date. League Commissioner Phil Woosnam, among others, recognizes the importance to the sport and to his organization of maintaining a franchise in Washington. Ever since the sellout Soccer Bowl '80 at RFK Stadium in September -- for which the region's civic and business groups guaranteed and delivered sales of 40,000 tickets -- Mr. Woosnam and other league officials have been lavish in their praise of Washington as a sports town.

And well they should be: this year, attendance at Dips games here doubled that of last year, and last year's doubled the previous year's count. In fact, Washington is currently the league's fifth fest market in attendance. Indications point to a growing market, too, with some 120,000 youngsters now playing in organized leagues around the region. So even though Diplomats President Stephen I. Danzansky is known to be incurably soft on his native city and its potential for greatness, his business sense also has spurred him to work furiously over the last few days in search of investors to join him in sustaining the team. He is the first to note that the franchise won't be an immediate profit-maker; what it would take, he says, are investors with confidence and patience who have faith in the region's future. But this kind of coalition doesn't materialize in a matter of weeks. Reasonable time is needed, and Commissioner Woosnam should lead the effort to accord it.