The week-long National Cherry Blossom Festival kicks off unofficially Sunday with the Nike Cherry Blossom 10 Mile, one of the top road races in the country. Though it's too late to register for the 10-miler, you can still join in a 3,000-meter fun run, which begins shortly after 8 a.m. in West Potomac Park near the Lincoln Memorial. The first thousand finishers will receive a patch in this free race.. And you won't even have to worry about being trampled by the herd of 5,000 serious racers representing a dozen different countries, because they'll be taking off just before you. 445-4177.

By the way, there'll be a variety of other festival-related events throughout the week, including a Japanese lantern lighting ceremony near the Jefferson Memorial Sunday from 4 to 6; concerts in various parks around town from Monday through Friday; an exhibition tennis match on Monday between Boris Becker and Guillermo Vilas at George Washington University; and a free big-band tea dance Wednesday from 8 to 10 at the Sylvan Theater near the Washington Monument. The parade is Saturday April 12. For schedule and details, call 789-7070.