Because she is so gifted, athletic and competitive, Martina Navratilova has always made tennis look easy.

Like Billie Jean King, whom she idolized, she seemed to have been born moving to the net, swiftly and instinctively. And like the Billie Jean King of the early '50s, the teen-age Navratilova was chubby, fiery, demonstrative and immature.

She played purely on talent and inspiration, and had enough of both to rank among the top half-dozen women players in th world at 15. But she was inconsistent. She couldn't cope with bad breaks or defeat. She dissolved into tears and tantrums frequently.

In retrospect, at the wise old age of 23, she even has adopted King's phrase to describe her youthful state of mind: "I didn't have a clue."

The public and the press often were hard on Navratilova. They couldn't understand why someone with such immense natural abilities often acted like a spoiled child, a crybaby.

But it wasn't easy for her, of course. It never is for one whose aspiration soar beyond the stars. And surely not for an emotional young woman from Czechoslovakia who realized that if she were to fulfill her ambitions she would have to defect from her homeland, leaving her parents and younger sister behind.

Navratilova defected and applied for U.S. citizenship during the U.S. Open tennis championships in September 1975. But it wasn't until she dominated women's tennis for the first six months of 1978 and won Wimbledon last July -- demonstrating a newfound maturity that is largely attributable to the friendship and support of her business manager and traveling companion, former pro golfer Sandra Haynie that the public came to appreciate just how difficult a period of adjustment Navratilova had been through.

"It still is difficult because I can't see my family. Even though I've achieved most everything I've ever wanted to achieve, I'm not completely happy, and I never will be until I have them with me, or I'm with them somewhere," Navratilova said yesterday, an idle day for her in the $125,000 Avon championships at George Washington University's Smith Center.

"I've had some good friends here in the States that have helped me a lot. Without them I don't think I coul dhave done it. I probably would have gone back to Czechoslovakia because I would have gone crazy. But I have some real dear friends that helped me through the bad times and stuck it out with me. "I'll never forget that.

"And, of course, starting to play better tennis helped me a lot. It kind of helps you forget a little bit. It makes your life look a little better overall."

It was for tennis, to be abel to pursue her dreams, that Navratilova defected.

When she first came to the United States at age 15 -- a bubbly extrovert who made friends instantly, even before she learned English -- she started to recognize the possibilities.

She also promptly developed a rapport with American players, a fondness for junk food and pop culture, and expensive tastes in designer jeans, Gucci accessories, gold jewelry and imported sports cars.

The Czechoslovakian tennis federation observed all this and concluded that Thoroughly Modern Martina had become "too Americanized." They cut back her international tournament schedule and threatened to revoke her visa.

But having learned to fly free, Navratilova could never go back to being a captive. She weighed the possibilities, decided that there probably would be no reprisals against her family and asked for political asylum in America.

She has not seen her parents, nor her teen-age sister Jana, since the summer of '75.

She talks to them by phone regularly, sends and receives letters and packages, but has been unsuccessful in helping them secure either a permanent visa, so they could join her in her adopted hometown of Dallas, or a tourist visa so they could visit her in Germany. It was there that they watched her Wimbledon triumph last summer since it was all but ignored in the government-controlled Czechoslovakian media.

Navratilova had hoped that winning the most prestigious of tournaments, with its worldwide exposure, would help her get her parents out of Czechoslovakia.

"It didn't," she says now. "Nothing has changed."

According to a treaty between the U.S. and Czechoslovakia, exptariate Czechs can visit their families after they become American citizens. For Navratilova, that will be another 22 months.

Last year she petitioned Congress to have the five-year residency requirement for citizenship waived so that she could represent the U.S. in international tennis competitions. The petition met a procedural death and Navratilova, now so composed on the tennis court, broke into uncontrollable sobs outside the House of Representatives visitors' gallery.

"We're not going to try again this year," she said. "It was too emotional I was like a yoyo, and it didn't get me anywhere. I'll wait the rest of the five years."

Once again she hopes that playing better tennis will ease the burden of waiting, and make her life seem a little better overall.

Winning Wimbledon was a supreme goal, but that is history.

"God, it seems so long ago. I don't think about it much unless I see a picture or somebody reminds me of it," she said. "I remember every point, but to keep dwelling on it would be like living in the past. You can't really do that."

People remember what you have done lately, as she discovered when the three-woman panel appointed by the International Tennis Federation to select an official world champion, and the respected World Tennis Magazine, both named Chris Evert the No. 1 player of 1978.

Evert won the U.S. Open and her last 32 matches of the year, three of them against Navratilova, thereby neutralizing Navratilova's two midsummer victories over her, including the Wimbledon final.

Navratilova is still No. 1 in the computer rankings of the Women's Tennis Association, having supplanted Evert at the top of the biweekly printout for the first time in four years last summer. But there is human dissent from the machine's opinion.

While Evert took a four-month vacation from tennis at the beginning of the year, Navratilova went on a rampage. She won seven consecutive tournaments, 37 straight matches, at the start of 1978. When Evert returned, Navratilova came from 1-4 and a match point down in the final set to beat her in a pre-Wimbledon tournament at Eastbourne, England, and from 2-4 down in the final set to beat her in the Wimbledon title match.

But from the euphoria of that moment, the rest of Navratilova's 1978 was something of a bummer. She injured her left shoulder. She played too much. And she became complacent.

"It wasn't conscious, I didn't do it on purpose, but I'm sure it happened," she said.

Navratilova won only one tournament the rest of the year, finishing with an 80-9 record and 11 tournament victories. Pam Shriver, age 16, beat her in the semifinals of the U.S. Open, one of the most startling major tournament upsets in the history of women's tennis.

"I had lots of mental and physical problems after Wimbledon," Navratilova said. cI burned myself out in World Team Tennis, and even though I had a great record it didn't help my ranking. Nobody gave a hoot.

"My shoulder started hurting. I got an injection of cortisone, but didn't take enough time off to let it work. I think the doctor missed the spot anyway. I could still play well and hit the ball pretty hard, but on some shots, when I stretched, it hurt more and more. It really started bothering me during the Open.

"I guess it was a good copout for me. Even though I didn't use it as an excuse, it was in the back of my mind: it was okay if I lost because my shoulder was bad. That was just a bad attitude.

"I kept playing even though I didn't want to be out there, and I don't play well when I don't feel like playing... I ended up losing to Chris the last three times we played, and that kind of blew the whole year."

She realized that when the rankings came out making Evert No. 1 on the basis of her 56-3 record, seven tournament victories and 3-2 edge over Navratilova head to head.

Navratilova thinks she should have been No. 1: cI dominated for eight months, Chris for three months. I think I deserved it. But some people disagreed."

Her goal for this year is to erase the doubts.

"My sense of purpose is very strong, and my mental state a lot better now," she said. "I want to be ranked No. 1, not only on the computer, but in the minds of every single person on this earth. I want no dispute about it, which means winning Wimbledon, and the U.S. Open, and dominating the whole year."

It will not be easy. But then again, it never has been as easy for Navratilova as it looked.