Who are Barbara Potter, Sylvia Hanika and Anne (Pepper) Smith?

Who are these three young, highly ranked and rising tennis players who have joined Martina Navratilova in the semifinals of the Avon Championships of Washington?

Potter, who upset Andrea Jaeger yesterday, ought to be the cover girl for the Preppie Handbook. Except that there's so much more to her than any simple label could indicate. Her grandfather won a Pulitzer Prize, her father is an oil painter and her great act of youthful rebellion, thus far, is deciding not to follow family tradition and go to Yale. She chose Princeton.

Hanika is an anonymous 22-year-old superstar of tennis. She's ranked sixth in the world, yet is so unknown in the United States that when she visited the White House this week, she simply stood in line for the regular public tour; nobody noticed her. That's Hanika's style: almost anti-charismatic.

The determined Smith, who backed her shocking upset of Tracy Austin in the second round with a surprise knockout of the fifth-seeded Shriver last night, is a one-week phenom who already has gone as far in this tournament as in any singles event of her pro life. She thinks the Smith Center is named for her. "I like this place," she said last night. "Why do we have to leave?"

Of the three, the 20-year-old Potter, ranked 10th in the world, is perhaps the most remarkable.

Yesterday, dressed all in bright pink and serving left-handed rockets at Jaeger, Potter was a picture of serious, knitted-brow Yankee purpose, a kind of severe Kate Hepburn whose only competitive smiles were little private ones that the crowd was not invited to share. Potter, a cheerful chatterbox when she's in the mood, is a no-nonsense, tennis-for-tennis-sake artiste.

"My father is an artist's artist: representational, not chic, a professional portrait painter somewhat in (Andrew) Wythe's style," she said. "I'm sure he could have made a ton of money if that's what had been important to him, but he wanted to paint, so he did." Her grandfather, Hanson Baldwin, was military editor of The New York Times during World War II.

"Looking at my father makes me realize that if you have a tune that you hear, you should follow it, no matter what other people think. Too many people don't have that 'luck of life' to follow their own tune. They say, 'It's too late for me. I better do some standard thing.' My parents aren't unorthodox, but they are broadminded."

Clearly, tennis is not the standard tune that Potter might be expected to hum. By the time she graduated from the Taft School in Connecticut and was accepted at Princeton, she had had several shows of her own, oils and water colors. But she decided to forego one love, painting, to see how far she could go as a pro athlete.

"My oldest brother is leading a varied and Bohemian life in New York . . . he's sort of a Steinbeck single man, not focused yet. Another brother is in politics, raising funds for George Bush's brother Prescott, who's running for a Senate seat from Connecticut. Another brother is an electrical engineer, reads those impossible textbooks like they were novels.

"I'm the dumb jock," she said, laughing, then added, "I'll get back to painting someday."

Until then, she's trying to master both her own temperament and her tactical game.

"Tennis shows the personality of the player," Potter said. "That's because the game is so full of shifting tides. Who hangs in. Who quits. Who tries to break the other player's will early, or who still has the stamina to do it late in the match. My style is creative and free, but I need to get better at concentrating on crucial points. That's where I seem to be improving now."

To Potter, Chris Evert Lloyd is "an engineer, but with imagination." Hana Mandlikova is "a flower girl of amazing gifts who sometimes lapses into concentration."

And what of Navratilova, whom she meets today.

"She's our Hercules," said Potter.

Of all the world's top players, the West German Hanika seems to have the most natural camouflage. Despite her high ranking and $190,898 in winnings last year, the clay-courter never has made a ripple at Wimbledon and never gone higher than the quarterfinals (twice) at the U.S. Open. Her best moments, reaching the finals, have come at the French and Italian opens, which many Americans tend to regard as sporting events on the same order as the Astro-Bluebonnet Bowl.

On court, Hanika is a powerful groundstroker who sometimes has spectacularly erratic days.

"When I play badly, what goes first? Everything," she said. "Then, it is hopeless." Most of the time, that's how her opponents feel against the stoic, patient left-hander.