Guillermo Vilas, a longtime success story in the annual clay court tournaments in Washington, D.C., will highlight a field of 56 players when the $279,000 Sovran Bank/D.C. National Tennis Classic begins Monday.

First-round matches will begin at noon on Monday at Rock Creek Tennis Stadium, located at 16th and Kennedy streets. The quarterfinals will be played Friday at noon and 7 p.m., the semifinals Saturday at 1 and 7 p.m. and the finals Sunday at 7 p.m.

Vilas, who this year reached the quarterfinals of the French Open and the final of the Tournament of Champions, is the No. 4 seed and will be competing against some formidable opponents. Andres Gomez, winner in this tournament in 1984, is the top seed, followed by Thierry Tulasne and Martin Jaite. Aaron Krickstein, Jimmy Arias, and Henrik Sundstrom also have strong clay credentials.

One top contender will be missing, however. Yannick Noah, the defending champion, withdrew Friday because of an ankle injury.

Much attention will be focused on Vilas, who won the singles title here in 1975, 1977 and 1979 but by 1984 had fallen to No. 43 in the world. In recent months, his ranking has risen to No. 18, and with it his hopes of winning a fourth title in the District.

It is the ninth tournament appearance here for Vilas, who was ranked as high as second (1975 and '77) in his career. He has won four Grand Slam titles: the French Open and U.S. Open in 1977 and the Australian Open in 1978 and 1979.