When Martina Navratilova walks onto the court Tuesday to begin yet another tennis tournament in a life full of tennis tournaments, she will have reached the end of a long journey.

And because she is such an emotional person, Navratilova will be keenly aware of everything around her. She will hear the crowd, she will notice the way people are looking at her and undoubtedly will experience a mixture of pride, joy and sadness.

She will be home, back in Czechoslovakia 11 years after she defected to the United States. She left a confused, chubby teen-ager, full of hopes and dreams. She returns a mature woman who has lived many of those dreams and survived nightmares she never could have imagined when she left.

But most important, she has come back, as a U.S. citizen, representing her adopted country in the Federation Cup. The 43-nation women's version of the Davis Cup begins here Sunday and Navratilova and Chris Evert Lloyd will play singles for the United States starting Tuesday.

"I really don't know what to expect," she said recently. "I think when we play against the Czechoslovakians, the people will root for them. That's understandable. But in other matches, I think it will be different. I'm still kind of a hero to them. I don't think, even though I left, they feel betrayed. They understand why I did what I did. I'm still Martina. That hasn't changed."

But she has changed. When she defected in 1975, she was almost 5 feet 8, weighed 155 pounds and had wild brown hair. A year later she was up to 167. Today, she is 145 pounds with stylish, shoulder-length blond hair and an easy, warm smile. She has gone from a chunky powerhouse who blasted the ball all over the court to a disciplined and extraordinary tennis player, one of the greatest of all time.

That has been the easy part. The hard part has been the growing up. She has had to deal with acute loneliness, with accepting her bisexuality and the fact that many others cannot, or will not, accept it. She has felt rejected and confused. Even now, with fame and fortune, she cannot understand why tennis fans don't like her more.

"It doesn't affect the way I play at all," she said. "I know it's not anything personal a lot of the time. People root for underdogs. But when it goes on match after match it gets you down. It would never cause me to lose a match, but I would enjoy it more if the people were more objective. More fair."

It is impossible to mention Navratilova without discussing Evert. The two are linked by longevity, by greatness and by competitiveness.

Yet they have such different images. Navratilova, especially on the court, looks so hard, so tough. Yet inside, she is soft, vulnerable, lost without her friends and family.

Evert looks so much like the sweet little girl next door. But inside she is the hard one; tough-minded, always the boss. Navratilova always is looking over to where her friends are seated during a match, seeking support. Evert's eyes never wander. She needs little outside help.

Because they are friends, because they like and respect one another, Navratilova always is cautious when she talks about Evert. But occasionally, a trace of discord will slip in.

When discussing her progression as a player, she can't get by 1978 without mentioning that Evert was ranked No. 1 that year by the International Tennis Federation. "That was the first year I had a winning record against Chris," she said. "I should have been No. 1, but they gave it to her because she was No. 1 the year before. They said I wasn't convincing enough to displace her. Like boxing. Which is ridiculous because in tennis you judge from year to year."

No big deal. But she remembered.

Evert was the guidepost Navratilova set up for herself as she climbed to the top. When Navratilova passed her and began dominating, Evert used her in the same way. Now, Evert has learned to live with being a very good No. 2. Navratilova has come to accept the fact that on a given day at a given place (most likely the clay of Paris) Evert still can beat her.

But the way people react to them still unnerves Navratilova. Intellectually, she understands that people pull for underdogs. But she aches when she thinks people like Evert more than they like her.

"I'm too logical about crowds," she said. "I don't think people should root for someone to fail. I just can't understand that. It does not compute.

"I really think that I'm a good person. The heart is what matters and not anything else really. It shouldn't matter how you look, how you talk, whether you have an accent or come from America or whether you're the girl next door or put fingernail polish on your nails."

And, although Navratilova never brings it up, there is one other thing that affects the way people perceive the two women: sexuality.

Even though her marriage has had rocky times, Evert always has been the glamor girl, dating people such as Jimmy Connors, Jack Ford and Burt Reynolds before marrying blond-haired, blue-eyed John Lloyd.

Navratilova, who first talked about bisexuality in her book, "Martina," travels now with former Texas beauty queen Judy Nelson. Often, Nelson's two sons travel with them. The Navratilova-Nelson relationship is two years old and people connected with the women's tour say Nelson has been a positive force in Navratilova's life, a settling influence.

"I think if I was married, there would be a lot more people pulling for me because they would not feel so threatened by who I am and what I do," Navratilova said.

"It's sad when people judge you for things like that. Maybe, because some people have come to accept me for who I am, I've helped curb some prejudices. But I think Americans have a need to put people into categories. They want to put a label on them and put them neatly into some drawer. If you don't quite belong somewhere, they get all thrown off because they don't know how to deal with you. That's the problem. People feel threatened by things they don't understand or don't know."

If she is, understandably, a bit reticent in talking about her personal life, Navratilova, who will turn 30 in three months, is not the least bit shy when the subject is her professional life.

She is justifiably proud of her accomplishments and the hard work that produced them. She has won seven Wimbledons, including the last five, and 14 Grand Slam singles titles. That puts her four behind Evert's record of 18. She has won 31 total Grand Slam titles and 15 total Wimbledon titles, the latter five short of Billie Jean King's record of 20. But she says she is proudest of her record-breaking 74-match winning streak of two years ago. The old record holder? Evert, with 55.

"I think that's the one that stands out for me," Navratilova said. " . . . I feel like that's a record that will never be touched, like Joe DiMaggio's 56-game hitting streak."

She is conscious of records. She would like to break King's record and Helen Wills Moody's record of eight Wimbledon singles championships. She would love to surpass Evert in Grand Slam victories. There is pride in her voice when she talks about her tennis.

"I feel lucky because I had the body to be good and I did the work," she said. "I had a jump start because I believe I'm a better athlete than anybody out there. But I also did the work. Chris has done the work, too, the last few years but I had a lap lead on her. She wins with pride now, but she's been doing that for a long time."

When Navratilova won six straight Grand Slam titles in 1983 and 1984 and beat Evert 13 straight times, both women undoubtedly believed that the rivalry was over. But Evert has come back to win the French Open the last two years, beating Navratilova in a classic final in 1985 and a good one in 1986.

But all this comes after Navratilova has won the more important battle -- the one with herself. Her first six years after defecting were a roller coaster ride on and off the court.

"The first few months after I defected were exciting," she remembered. "But then I started to have injury troubles. I hurt my wrist and kept playing. Then I hurt an ankle and had to stop, which was probably good for my wrist. But I played too much that summer, team tennis killed me. By the time I got to the U.S. Open, I was exhausted. When I lost in the first round, it really wasn't a surprise."

But it hurt. After that match, Navratilova sat on her chair and cried. "It just sort of all kicked in on me there," she said. "I was physically drained, emotionally drained. I thought, 'It's been a year and this is it. This is where I am.' I had nobody to lean on. I couldn't see my family, they couldn't see me. I was all alone. Where do you go? I was 19. That's pretty young."

Briefly, the thought of returning flashed through her mind. "But that lasted about five minutes." Instead, she slowly put her life in order. She lost 20 pounds in 1977 and in 1978 won her first Wimbledon, beating Evert in the final. She won another Wimbledon in 1979, but then slipped a bit.

Her muddled personal life, her stepfather's inability (as she writes in her book) to deal at first with the concept of her bisexuality, combined to hurt her tennis. She never played poorly, but Evert, Tracy Austin, even Andrea Jaeger and Hana Mandlikova, all eclipsed her during 1980 and 1981.

Then, in the summer of 1981, she began her new training program. She became stronger and tougher, coached by Renee Richards and Nancy Lieberman. Both helped her game -- Richards with technique, Lieberman with competitiveness. That fall, at the U.S. Open, she upset Evert in the semifinals and lost a classic three-set final to Austin.

At that tournament, she first won the fans. She was an underdog then and they were all for her during the final. When they cheered her as she accepted her second-place trophy, Navratilova wept.

Her tennis improved steadily from that point. Even when the Richards-Lieberman team broke up and she hired Mike Estep as her new coach, her tennis kept getting better. Estep worked mostly on technique, on getting her to use her athletic ability to her utmost.

"The best thing about her," he said, "is that she's such a willing pupil. She always wants to learn, always wants to get better."

All the work produced The Streak of 1984 and her dominance of the game.

"If all the other girls were still playing the way they did in 1984, I think I would still be beating them the way I did then, maybe worse," she said. "But they've gotten better. There are girls playing like me now, serving and volleying, and Chris has gotten better, too. But I'm a better tennis player than I was then.

"I may not be quite as eager, even though I'm still eager. But the hunger isn't quite the same. I've still got it, but not like I did then."

She still is hungry. But not starving.

Following the advice of friends, Navratilova has steered away from the subject of her trip back to Czechoslovakia during the last few weeks. "When it first came up, a lot of people didn't think I should go," she said. "I just called my dad and asked if it was all right. He said it was fine, come. So it was fine. If he had told me it wasn't, I wouldn't have gone no matter what anybody else said.

"It really doesn't worry me. I read the papers and I know that what Americans say about Communist countries is not so and I know what the Russians are writing about Americans is not so. I've been on both sides of the fence. We get as lopsided a view in the U.S. as they do over there.

"I got my visa as soon as we applied for it as a team. I didn't expect a problem. I've been invited many, many times by the people in the Czech federation to visit to play exhibitions, so I guess they want me to play there."

Why hadn't she gone before?

"I thought something like this would be better, safer, I guess."

Her welcome yesterday could not have been much warmer. She was met at the Prague airport by her parents, plenty of media and security people and -- despite a steady rain -- autograph seekers.

In mid-afternoon she went with her parents to their home, about 30 minutes from Prague, where she hopes to take teammates Evert, Pam Shriver and Zina Garrison for a visit.

This week, she will be the star.

She comes home a champion.

"I don't know what it will be like until I get there," she had said. "But I'm looking forward to it."

Navratilova had talked about herself through most of an evening. This was at Eastbourne, the week before Wimbledon, in a small country restaurant she takes her friends to every year. She had allowed herself a glass of white wine and one bite of duck. Those were the only breaks from her training regimen.

Now, it was almost time to go. She was wrapping up. "I know the end is near for me," she said. "Sometimes, I think one year, sometimes I think five years. Sometimes I think I never want to see another tennis ball.

"But if I quit now, I would have the itch to play again in two weeks. I know that. I hope, when I stop, people will think that somehow I mattered. That's important to me. I get letters from people saying I inspired them to lose weight or I've inspired them to work harder in school or to get out of a wheelchair and walk. To overcome things. To me, that's it. To reach people beyond tennis.

"I like knowing that I've always given the game a good shot. I've come a long way to get here. Sometimes, I think why me? There must be a reason. I deserve what I've got. I'm lucky. I have a good mind and a good body. Those two don't always go together. I've been pretty lucky. Very lucky."