One year ago, Pam Shriver came to Washington to play in her first professional tennis tournament. Her coach, Don Candy, drove her from home in Lutherville, Md. Pam, at age 15, was too young to have a driver's license. She was delighted to qualify for the main draw and win one round.

This week she returns to the same tournament-formerly sponsored by Virginia Slims, now the $125,000 Avon Championships of Washington-as one of eight seeded players. She's an international celebrity since becoming the youngest finalist in the history of the U.S. Open Championships last September.

That is a measure of how far Shriver-still an amateur until she finishes her combined junior and senior years at Baltimore's McDonogh School in June-has come in 12 months. And it is a reflection of a revolution taking place in women's tennis.

Youngers are maturing so rapidly that Wimbledon champion Martina Navratilova feels on the older side of a generation gap at 22. The sunshine girls of the early '70s-U.S. Open champ Crhis Evert, 24, and Yvonne Goolagong, 27-seem like middle-aged matrons.

Meanwhile, the over-30 regulars, such as Billie Jean King, Virginia Wade, Rosemary Casals, Betty Stove and Francoise Durr, feel absolutely ancient, like living relics, pioneers from the days of tennis' Civil War.

Evert, Goolagong, Wade, King, Kerry Reid and several other familiar names decided to bypass Washington this year. They will be missed.But "the kids," as they call the ascending generation, should provide a good show.

Shriver joins Tracy Austin, the California prodigy who turned 16 this month and is making her debut here. They are the youngest and most accomplished of 10 teen-agers in the 32-woman field for the tournament that begins Monday at 10 a.m. Play continues through next Sunday at George Washington University's Smith Center.

Austin is seeded No. 2, behind Navratilova, the winner here in 1975-77-78.

Austin plays her first match Wednesday evening against Californian Barbara Hallquist, 21. Navratilova's first-round opponent Tuesday night is Lea Antonoplis, 19, the junior Wimbledon champion of 1977.

Shriver is the No. 7 seed, behind Stove, Australian Dianne Fromholtz, Casals, and Romanian Virginia Ruzici, who beat Shriver in the second round last year.

There are several other talented teens who bear watching, most notably Anne Smith, 19, a wonderfully athletic, aggressive player from Dallas; Hana Strachanova, 18, of Czechoslovakia; Peanut Louie, 18, of San Francisco, and Caroline Stoll, 18, of Morristown, N.J., who has patterned her exaggerated top-spin strokes after Bjorn Borg.

Perhaps the best first-round match will be Tuesday at 5 p.m., when Smith plays Stove, 33, the Wimbledon runner-up of 1977. Following that match, Shriver faces a stern opening test against Durr, 36, the colorful Frenchwoman with the pitty-pat serve, bizarre strokes and opportunistic tactical mind.

Entries were accepted according to the computer rankings of the U.S. Tennis Association. Four of the top 10, nine of the top 20, 15 of the 30 entered Washington. Interestingly, 20 of the 30 players accepted directly into the draw are 23 years old or younger.

That seems appropriate since Washington is the first stop on the 11-tournament, $1.9 million Avon Championship Tennis series. It culminates in a $275,000 playoff at New York's Madison Square Garden in March. Avon has taken over sponsorship of the major Women's winter tour after three years of sponsoring the "Futures" satellite circuit, developing and proving grounds for young talent.

Shriver, who has yet to beat Austin in junior tournaments, will get her 10th chance in Friday's quarterfinals if form holds true to the seedings.

Shriver has not played competitively since the Wightman Cup matches against Great Britain in London in October, however, concentrating instead on algebra and the like.

Austin; who turned pro Oct. 19 and has won more than $30,000 in prize money, has combined travel and tournaments with her 10th grade classes at Rolling Hills (Calif.) High School. She is a straight A student.

She beat Stove in the final of her of first tournament as a pro, at Stuttgart, West Germany, then whipped Navratilova for the $20,000 first prize in an eight-woman tournament in Japan last month.

Shriver beat Navratilova, No: 1 in the computer rankings, in the semifinals of the U.S. Open when she should have been back in Baltimore for the opening week of school.

No wonder Navratilova feels aged at 22.