To be perfectly honest about it, Leslie Allen was not noticed because she is novel, exciting, attractive, articulate, interesting, and decidedly different in background from most of her colleagues on the women's professional tennis tour: a 5-foot-10-inch panther at the net, clad in pastel tennis dresses of her own design.

If she didn't happen to be black, her victory early last month in an otherwise unexceptional $150,000 tournament in Detroit never would have received the attention it deserved for reasons that had nothing to do with color.

It was because Allen was the first black woman to win a significant tournament in 23 years, since Althea Gibson reigned as the Wimbledon and U.S. champion of 1958, that reports of her victory vaulted from the sports page to the front page of newspapers in Detroit, and gained national notice.

It is because she is making an impact in a still predominantly white game that Allen received far more attention than six other first-time qualifiers when the $300,000 Avon Championships, the eight-woman playoff for the top finishers on the winter women's tour, convened at Madison Square Garden last week.

It didn't matter that she didn't make the semifinals. In the absence of usual headliners Chris Evert Lloyd and Tracy Austin, who didn't play the winter circuit, Allen was a focal point of the tournament publicity mill. "The Harlem girl," as she smilingly characterized herself, referringg to the renovated 12-room brownstone she recently purchased with her mother on West 139th Street, "who came downtown to play tennis at the Garden."

Yet her color really is irrelevant, and Allen knows it. She comes from a middle-class, well-educated background, and is in no sense a child of the ghetto. What makes her story fascinating is the improbable, circuitous route by which she arrived in pro tennis and her current circumstances.

For a long time, she despised the game. She didn't take it seriously until her senior year in high school. Then she embarked on a curious four-year odyssey through four colleges: Carnegie-Mellon Institute in Pittsburgh, New York's Fashion Institute of Technology, Texas Southern and Southern Cal, from which she was graduated magna cum laude in 1977 with a major in speech communications.

Only now at 24 -- the age at which Evert started thinking about retirement -- is Allen coming to grips with her potential. "I don't think I've started to approach the limits of my ability," she says. "There are still shots that I'm learning to hit. I want to see how good I can be, because I don't think I have any idea yet, and that's encouraging."

What was remarkable about Allen's victory in Detroit was that just two weeks earlier, she was toiling on the Avon "Futures" circuit, the satellite tour that is the off-Broadway of women's tennis. Only by reaching the semifinals of a "Futures" event in Montreal did she earn a place in the Detroit draw. There she upset three seeded players, including Hana Mandlikova of Czechoslovakia in the final, to win the $24,000 top prize.

Never before had a woman qualified for a major circuit tournament via the "Futures," and promptly won the main event. Here was a vivid practical demonstration of how the system that enables young women to break into big-time tennis works in theory.

"I don't think people in the tennis world, who followed what was going on, were really stunned," says Allen. "Most of them thought, 'Well, Leslie finally played the way she can.' "It was the people who had never heard of me, who don't pay that much attention to tennis, who got up on Monday morning, looked at their papers, and said: 'What's this? Some black girl won a tennis tournament? Where did she come from?' That's only natural."

She does not see herself as a role model only for blacks, but for any youngster with aspirations that seem unrealistic to the world. "My story is kind of different from the usual. There are other black players out here (five currently on the "Futures" circuit), and most of them have followed the traditional pattern, playing in the junior ranks, in college, working their way up to the pros. But when you kind of come out of nowhere, like I did, it makes people think. Maybe I an motivate some kids, and get people interested in tennis who never were before."

Allen is a gifted natural athlete -- powerful, quick, if not especially agile -- but she never played any sport seriously until she was 16.

She was exposed to tennis early by her mother, a tall, handsome and intelligent woman, who used to teach school in Cleveland and Washington, and play tournaments all summer.

Leslie was a captive audience. Her mother was divorced, and dragged her to the courts. "I wasn't going to leave her at home alone, and frequently I didn't come off court until dark because I won," says Sarah Allen, who left education and became a successful marketing executive, then gave that up for a modest career as a Broadway actress because that is what she always wanted to do. ""Leslie was sitting by the court when she wanted to play in the sandbox."

Even though she was not allowed to play in many of the swanky clubs that then were bastions of the tennis establishment, Sarah Allen loved the game "when it was classy, elegant, everyone dressed all in white and was well-mannered."

Leslie saw it differently. "None of my friends played," she remembers. "It was sort of a sissy country club sport that nobody who was any kind of an athlete, black or white, played. You just stood there in those little dresses and pooped the ball back and forth, running around on grass. What was that?

"I retired when I was 11, played a little again when I was 13, then retired again," she says. "When I was 14 and 15, and went away to visit friends in Florida and Vermont in the summer, I never took my racket out of my suitcase. People who knew me then say I was the last person they'd ever expect to become a professional tennis player because I hate it so much."

It wasnt't until 1973, at age 16, that she picked up the game again. Having skipped kindergarten and third grade, and taken accelerated courses at a variety of schools (predominantly white private and parochial schools in several cities, a black boarding school in North Carolina), she found herself able to graduate from high school, but not yet ready to go to college.

She had decided to live for a while in Cleveland with her father, stepmother and half-brother, whom she had regarded as her "second family." Even though she had fulfilled all requirements, she stayed on for her senior year at Glenville High School, taking junior college courses and looking for other activities to occupy her time.

A girl could be a majorette, sing in the choir, or march in the band, but I couldn't twirl a baton, carry a tune or play an instrument," she says. "I decided to try sports, but they didn't have any girls teams.

"That was the fall Chris Evert was doing so well, Billie Jean King beat Bobby Riggs, and tennis was suddenly the hot sport. Everybody was getting new rackets, new outfits, getting ecstatic about tennis, and I thought: 'Wait a minute, is this the same sport I loathed?' I went to the closet and dug out the same racket I had when I was 11, with the same strings, and started playing."

She wanted to play on the boys team, and since there were no decent players at Glenville at the time, could have held her own. Initially, she was told that girls could not play, but this was the time that women's lib and Title IX were emerging.

The Women's Law Fund took up her case. The day before the state high school tournament, the Ohio Athletic Association, facing a court case, accepting her entry. She won one round, against a substitute who was not good enough to get into the tournament originally, and became, unintentionally, a cause celebre.

The next year she went to prestigious Carnegie-Mellon on an academic scholarship, but now she had caught the tennis bug. The women's team there was strictly small time, playing a few matches against local schools. Allen didn't have a car, and her tennis was mostly limited to two hours of doubles on Saturday nights, 9 to 11, with one of her instructors.

The summer after her freshman year she played at a club in New York, across the street from the Fashion Institute of Technology, and made some money designing and selling tennis clothes. Just before it was time to return to Carnegie-Mellon, she decided to transfer to F.I.T., which had a women's team and would enable her to keep playing in New York. The day after classes began, she walked in off the street, a portfolio of sketches and her tennis designs under her arm, and was accepted.

She stayed one semester, then decided that 9-to-4 classes followed by projects left too little time for tennis. "I figured you could read a history book or write a term paper at the club between workouts, but you couldn't set up your easel and paints or cut fabrics there," she said.

Friends talked her into joining them at Texas Southern, where she got into the best shape of her life by training with the track team, but was frustrated when a promised women's tennis team didn't materialize. The track coach offered her a scholarship even though she had never run an event, and had no desire to, but she decided it was time to move on again.

She spent the summer in California with her her mother and just before Labor Day happened onto the Southern California campus in Los Angeles. The school and the tennis program appealed to her. She walked in unannounced, talked to the director of women's athletics, wrote her transcript out on a piece of notebook paper, walked it over to the admissions office in her tennis clothes, and was accepted with a scholarship -- part academic, part athletic -- the same day.

Improving steadily her two years at USC, she played No. 5 singles on the team that won the national women's intercollegiate title in 1977. Even though she didn't make the four-woman traveling squad, she played almost even with all-America teammates Diane Desfor, Barbara Hallquist, Sheila McInerney and Gretchen Galt, and started thinking seriously about a pro tennis career.

Three years earlier, when the thought had first crossed her mind, she was careful "not to say it too loud, because if the neighbors had heard, they'd have died laughing." Her mother was just as skeptical, but offered only encouragement, as is her wont.

"There was no way I could believe Leslie could become a professional tennis player. She couldn't play at all," Sarah Allen says now, "but I was not about to tell her that."

After all, she believed in reaching out in whatever directions the heart prompted.

Sarah had wanted to be an actress since she was 6, but her parents didn't consider that a proper vocation for a "nice girl." She went to Central State College in Ohio, studied premed, became a teacher, then a science consultant for the Washington public schools. On the side she studied, then went into, modeling, public relations and marketing. Corporate America was just starting to court what was then called "the Negro market," and she landed a high-paying job with General Foods.

After studying nights at the American Academy of Dramatic Arts in Manhattan, she was offered a full-time scholarship, and gave up her executive career to go into the theater. "I didn't want to put Leslie in the position where I might have said to her 10 years later, 'if it wasn't for you, I might have been a great actress,'" says Sarah Allen, who has enjoyed an unmomentous but satisfying career in the theater, "I believe everyone should be allowed to take the chance to fail.

"If i handn't taken the opportunity to go into acting, it would have always stuck in my craw. When the time came that Leslie announced she wanted to play professional tennis, and I knew she couldn't play at all, I wasn't going to discourage her. I was going to allow her to have that opportunity to fail. And a lot of times when you have that luxury of failing, you succeed."