When Alexandra Stevenson was 6 months old, her mother took her to a swimming specialist, who threw her in a pool. By 12 months she was swimming several feet through the water. At 18 months she was doing multiple flips underwater, without coming up for a breath. At 2 she was competing in local races in her home town of La Jolla, Calif.

That was before preschool. By the time she got to first grade, Stevenson was doing gymnastics, ballet, had tried ice skating. A couple of years later she was playing soccer, too. And from the start, tennis. Always tennis. She had a racket at 3 1/2. By age 9 she was taking lessons twice a week.

"It wasn't intensive," insists her mother, Samantha, watching her daughter hammer backhands across the court to her coach, Craig Kardon. "All my friends were doing the same thing. It was the '80s. We were power moms. We were making sure our kids were brilliant in the classroom and brilliant in the field."

Except that Alexandra Stevenson wasn't like all the kids growing up in La Jolla, a wealthy, conservative, white enclave of Southern California. She was a biracial child being raised by a white mother. She had no father at home. She wasn't wealthy.

And Stevenson hasn't turned out like all the other kids either. Next week the 6-foot-1 18-year-old will be playing in the U.S. Open, her first Grand Slam tournament since she stunned the tennis world eight weeks ago by blasting her way to the semifinals at Wimbledon--after having to play several matches just to qualify for the tournament. She was the first female qualifier to get so far at Wimbledon.

But a bigger bombshell had come earlier that week: The Fort Lauderdale Sun-Sentinel broke the news that Stevenson was the unacknowledged daughter of legendary basketball player Julius "Dr. J." Erving, who is married and has four other children. After first denying the story, Erving acknowledged his paternity, stemming from a relationship he had had with Stevenson's mother, a sports journalist, in the 1970s. He said he had supported his daughter financially over the years and had seen her once. Then he went back to his life.

Stevenson's life, however, has not been the same, nor can it be. All of a sudden people want to know who she is, where she came from and how she feels about the father she never knew. It is a wrenching irony: Throughout her life Alexandra Stevenson was groomed and nurtured for this moment in the sports spotlight. And always her mother tried to protect her from the uncomfortable realities of the family's past. Then, just as she was stepping onto the world stage, it all came crashing into the open.

Is it fair? After all the hard work? The other night there it was again, on television, as the newscaster announced Stevenson's first-round loss in the New Haven Pilot Pen tournament--"Dr. J's daughter" had been eliminated. Like a sudden curse. Whose business it is anyway?

"I hate it," she says hotly over lunch, after practice and a long discussion about her childhood, her ambitions and her life since joining the pro tour in June. "I'm not his daughter. I'm Sam's daughter." She sighs. "Some stupid guard shouted at me, 'Dr. J!' I wanted to punch him." She never would, of course; Stevenson is far too poised, far too . . . nice.

"But you'll get that," she concludes. "I don't like it. I just ignore it. I just have to not listen."

Up to now, Alexandra Stevenson has been kept too busy to wonder about what--or who--might be missing from her life. Her mother sent her to an exclusive private school in La Jolla and filled Alexandra's afternoons with a dizzying series of activities--sports, but dance and voice lessons, too, and drama. She hopes to act someday, after her tennis career.

"She always kept me busy. She didn't want me to be bored," says Stevenson, wolfing down some chicken fingers before the waiter brings her a turkey club sandwich. It is 3 p.m., and she hasn't eaten since breakfast. "I wouldn't come home from school and just watch TV."

Her wiry curls are pulled back off her face into a topknot, and she is wearing a magnetized sling under a blue sweat shirt to soothe her shoulder after the practice workout. Stevenson did not play particularly well today, and she was testy on the court; now, however, she seems relaxed and good-natured, happy to answer questions. But she's just as happy to let her mother answer questions for her.

"The goal was always to keep her centered and secure," Samantha Stevenson puts in. She is fiftyish (she has decided to stop telling her age), blond and bears little resemblance, physically or otherwise, to her daughter. Where Samantha seems fierce, Alexandra seems demure. Where Samantha wears the lines of life's battles on her face, Alexandra--with her slightly pudgy cheeks and childlike smile--seems younger than her years.

But they appear as close as two people can be, a family of two in which Mom leads and Alexandra implicitly follows. Protective? To a fault. Samantha drew attention at Wimbledon even before Alexandra's big victories by making accusations of racism and "rampant lesbianism" on the junior and pro tours. Since Alexandra turned pro in July, Samantha has given up her freelance writing to stick close to her daughter on tour. "Any single parent would do that for their kid," she says. "She needs a support system, and for her, that's me."

From the start, Samantha made no secret of her ambitions for her child. In 1986, when Alexandra was 5, she wrote an article for World Tennis magazine about motherhood: "Even before she picked up a tennis racket, I saw myself at Centre Court, Wimbledon, clapping for my daughter." And in 1987 in the same magazine, she hinted that Alexandra's heredity might hold greatness. "What makes a champion?" she wrote. "Red Smith [a former New York Times sports columnist] once told me it's in the blood. I agree. A world-class athlete is born with the ability to be great. Alexandra has it. You do know if your child's got it."

It was a feeling reinforced over time, watching Alexandra play. Samantha says: "I could see her in the group lessons. I knew, I felt she could be in the Top 10 in the world." When Alexandra was 9, Samantha sought out Pete Fischer, a renowned Los Angeles coach who had trained Pete Sampras and others. She persuaded him to watch the girl play for 20 minutes. He stayed for two hours and pronounced: "She could be number one in the world." He then coached Stevenson for the next eight years, as mother and daughter commuted to Los Angeles three times a week, sleeping at the homes of friends to save money. She would call Fischer from courtside for advice when Alexandra was in competition on the junior tour; mother and daughter would share meals to pinch pennies.

But Alexandra insists that her motivation to win does not come from her mother or her coaches. She recalls losing a match at a local club before she was 10; she determined not to let it happen again. "I hated losing to this girl," she recalls. "I decided I wanted to be a tennis player." And later she adds, "I've just always wanted to be a champion. It has nothing to do with my family."

She subsequently won that tournament a half-dozen times over. And now, she intends to win a Wimbledon, a U.S. Open--she plans to go to the top of her sport. "I want to play," she says, her eyes glinting. "I want to win."

"She's a unique girl," says Kardon, who coached Martina Navratilova for six years. He is taking time out from his job as a USTA coach to work with Stevenson and is already credited with refining her game. "She's very motivated and believes in herself. She believes she'll win Wimbledon someday." He takes a beat. "I saw her before Wimbledon and I thought, 'My God, there's a lot of work to do.' But she learned quickly."

In the meantime, he says, what she needs to do is play, and play a lot. Most of the other women her age on the professional circuit have been playing full time for years, while Stevenson just graduated from high school in June. She has catching up to do.

But Kardon believes she has the physical and mental makings of a winner. "She doesn't play like anybody out there," he says. "She has her own style--very powerful ground strokes, a big first serve, athletic volleys. . . . She's roughly similar to Pete Sampras. When she plays well, she can beat anybody."

As for who she is, where she comes from, Alexandra seems entirely clear: She is her mother's daughter. She never missed having a father, she insists. Their family didn't dwell on the past. And they don't intend to dwell on it now.

Nonetheless, the past is there.

In 1980, Samantha Stevenson was a freelance journalist based in Philadelphia, covering the Philadelphia 76ers and other teams, when she discovered she was pregnant. It was a different time for women in sports, and Stevenson was known--she still is known--as an outspoken and sometimes controversial character. She had sued the Philadelphia Phillies to gain access to their locker room; they settled out of court and opened the door. She was one of only a handful of women--one who was unafraid to draw attention to herself--in an overwhelmingly male world.

Not everyone responded kindly. "The last part of newspapers that was a male club was sports, and there was resistance on the part of papers to women," says Washington Post columnist Tony Kornheiser, an old friend of Samantha Stevenson's. "The men in positions of hiring were in their late forties and fifties and didn't understand women in their twenties who wanted to be sportswriters."

And she was pregnant by a star player whom she covered, an ethical breach that has turned many of today's female sportswriters--who have occasionally endured accusations of sleeping with the athletes they cover--into her harshest critics. (A panel last month at the Association for Women in Sports Media was dedicated to discussing the "Stevenson case." She continues to attract criticism for having covered pro tennis for the New York Times while her daughter was playing tournaments.)

Indeed, many in Samantha Stevenson's position would have decided to have an abortion. Stevenson nearly did, and it haunted her after she finally decided to drop out and move back to her home town of La Jolla to have Alexandra.

"I used to wake up in a cold sweat when she was a baby, thinking about the fact that I thought about not having her," she says. "I was a career person. I was going to be a columnist and write books. . . . It was difficult. I had to become a new person. That's why I went full force into the mom stuff." She sits in the shade of the practice court, staring straight into space. She never married. She didn't complain. She poured everything into her kid in their one-bedroom apartment on the beach, in a building with the laundry room in the basement.

"Everything I ever did I did full force," she says finally. "I was determined this child would never lose out because I was her mother."

As for Alexandra, the teenager insists she never felt different from other kids. "I'm pretty normal. Most of my friends--their mom and dad are not in the same house, like my mom and me. There's a lot of divorce."

That's why she has no interest in meeting her father, she says. "It's not a part of my life," she explains. "I've happily led my life already. I have no curiosity."

She also didn't pine for African American culture in La Jolla. "I never really thought of myself as black," she says.

"But you respect it," her mother prods.

"I respect it--but I definitely don't choose to be black. I don't choose to be white either. I think it's stupid how people put a fixed value on you. I'm a person: I eat, breathe and sleep." Pause. "Don't you?"

Still, she would ask about her father occasionally. When she was 4, the teacher at preschool asked everyone to stand up and say what their father did; Alexandra repeated what her mother had told her--"It's our family's business"--and came home crying. Samantha showed her a picture of Erving and explained who he was. When Alexandra was 8, she asked why her father couldn't live with them; Samantha gently explained.

That same year she had seen her father at a basketball camp for the first time. Wearing a big name tag, she stood in line with other kids for an autographed ball, and when it came her turn, he merely asked whether she wanted one. She said no and walked away; that was it.

Was it painful? "It wasn't painful," she says simply, "It was rude."

After that the questions died down, says Samantha. "I'd told her so much. We still have conversations--it's not over. We all have our own private thoughts on this. We talk about it." But basically, she says, "we live a full life. We're happy. We're not into analyzing. We don't believe in psychologists. We're Christian. We read the Bible and find the answers there."

Erving has declined all media requests for comment since his statement during Wimbledon.

A few weeks ago Alexandra met a beach volleyball player at the Pan American Games, where she took the bronze trophy (a disappointment, she admits). Collin Smith. They chatted, they hung out. They made plans for a date.

This was the date: Alexandra, Collin, Samantha, coach Kardon, Alexandra's agent, Carlos Fleming, and a friend of Collin's. They all went to a fish restaurant in Hermosa Beach.

"It was her first time out, so I thought it was appropriate to chaperon," says Samantha blithely. Alexandra doesn't seem to mind.

"There's a procedure," Samantha continues.

"I guess that's fine," says the daughter, who admits never having been kissed, and never having dated, not yet.

"We had the procedure," says Samantha. "He came to the matches. I've gotten to know him. He's very respectful of me."

Could Alexandra conceivably have a date without her mother's permission? "She doesn't need my permission. But I'd hope we discuss it beforehand," Samantha says. "Just because a child is 18, it doesn't mean she doesn't need wisdom from Mom. But she makes her own decisions."

Five days to the U.S. Open. Alexandra is struggling during a practice set with Anne Kremer, a player from Luxembourg. She is wearing new shoes that Nike sent her (and with whom she is apparently close to an endorsement deal). She grunts as she smashes cross-court shots beneath a scorching midday sun. Her mother is fingering a printout of the roster for the U.S. Open but says Alexandra will not be allowed to know who she plays until the day before the match--coach's instructions. Alexandra takes a break and catches sight of the list.

"What is that?" she asks.

"It's nothing. It's notes."

"No it's not. It's the draw."

No answer.

"Who do I play?"

"Talk to Craig."

"Tell me."

"Talk to Craig."

"Is it a seed?"

"Ask Craig."

A few minutes later Kardon relents: She's playing France's Nathalie Tauziat, the tournament's 11th-seeded player. They agree that this is good news even though Alexandra is ranked only 43rd because Tauziat is about a decade older than Alexandra.

"It's good," says Alexandra.

"Damn right it's good," responds Kardon.

If anything, it's Samantha who is nagged by doubts. For all her efforts, for all her work to fill the space a father might have taken--could she have protected her daughter any more?

"I thought about that a lot," Samantha says. "If there would be a hole in her. I'd put men and women around her to be in our family life, so she'd understand--divorced friends. Adopted kids. . . . But I don't think there's anything you can do about that. It's something she has to find and tell me if there's a place that she needs to tell me about."

She pauses. "You'd have to be a not-very-smart person to think that there's not a place in her that's not protected," she says. "So I try building her up. Telling her more and more about why." Pause. "I think she'll come to grips with it when she falls in love and gets married."

Last year, Samantha took Alexandra to see "The Parent Trap," a remake of the hit Disney film about twins, one raised by their father, the other by their mother, who switch places so each can meet the parent she never knew. In the scene where one of the twins, Hallie, meets her father for the first time, she can't help saying "Dad" over and over: "Dad . . . I just like the sound of it, Dad."

Seated beside her daughter, Stevenson felt herself cringe, a familiar ache filling the pit of her stomach. " 'Dad, Dad, Dad'--I just thought I'd slide right under my seat, I got really tense," she recalls. But Alexandra seemed unperturbed, laughing through the moment.

After the film, Stevenson asked her daughter, "What did you think of that scene?"

Alexandra replied, "I didn't even think about it."

"It made me feel bad," Stevenson confessed.

But Alexandra just smiled her wholesome, grounded, I-know-who-I-am smile. "I didn't. Can we see it again?"

CAPTION: "We're not into analyzing": Samantha Stevenson, left, daughter Alexandra Stevenson, and Julius "Dr. J" Erving, the father absent throughout her life.

CAPTION: Winning smile: Alexandra Stevenson, just 18 and still baby-faced, takes a break from a number of TV interviews in New Haven, Conn., as a technician adjusts her earpiece.

CAPTION: Alexandra Stevenson, left, mother Samantha and teammate Lilia Osterloh look over nail polish choices at a Winnipeg, Manitoba, spa--the players plan a red-white-and-blue manicure for the Pan Am Games.