U.S. OPEN : Martina at a Loss for Plans : Tennis: After 7-5, 6-4 loss to Sukova, she says she will play in ‘94--but she’s uncertain after that.

Martina Navratilova will be 37 next month, which means you probably can count the number of U.S. Opens she has left on, say, your ring finger.

Navratilova has been coming to the U.S. Open for so long, she is often considered part of the scenery, like the net they stretch across the courts. But lately, she has been leaving it sort of early.

On the occasion of her 21st U.S. Open appearance Monday, Navratilova produced a 7-5, 6-4 fourth-round loss to Helena Sukova, a player she had beaten like whipped cream for most of her career.

It didn’t do much to change what Navratilova has been thinking about all year. That is, whether her future in tennis is going to last beyond 1994.

“Whether next year will be my last year or not, that is the choice,” said Navratilova, whose last three U.S. Opens have resulted in defeats in the fourth round in 1990, the final in 1991, the second round in 1992 and now the fourth around again.

Navratilova’s defeat also represented a historical footnote to the U.S. Open. There are no Americans in the women’s singles quarterfinals, which had never happened in the 112 years of the tournament.

Navratilova, who defected to the United States in 1975, became an American citizen six years later.

Against Sukova, who was 4-25 against Navratilova, there were just enough mistakes to cost her the match. Navratilova’s serve was shaky, but this time she could not overcome it with sharp volleys.

Meanwhile, Sukova spent the match knocking backhand passing shots into the corners. She also won 41 of 56 points at the net and looked very much like the player who pinned Navratilova with one of the most disheartening defeats of her career, in 1984.

That was at the Australian Open, where Sukova scored a 1-6, 6-3, 7-5 victory in the semifinals and ended Navratilova’s 74-match winning streak.

Navratilova found her mind wandering back to that nine-year-old match, which probably was a mistake since she happened to be playing a match at the same moment.

“I said, ‘You should be thinking about what you need to be doing,’ ” Navratilova said. “It is just ridiculous. That is what gets harder when you get older. You have so many more things to distract you.

“In the past, if didn’t really focus, I was dominating so much I could still get away with it and win the matches most of the time. Now I can’t do that.”

So it is Sukova, not Navratilova, who moves on to the quarterfinals and a match against Katerina Maleeva, who beat her sister, Magdalena, in straight sets.

Arantxa Sanchez Vicario breezed past Nathalie Tauziat and will meet Natalia Zvereva in the other quarterfinal in the bottom half of the draw.

Zvereva, who hasn’t been in a Grand Slam semifinal in five years, is one step away after defeating Maria Jose Gaidano, 6-0, 6-2, in the quarterfinals.

Once ranked No. 6 in the world, it has been a long, hard road back to the second week of the Grand Slams for Zvereva, who has been reeling ever since she lost, 6-0, 6-0, to Steffi Graf in the 1988 French Open final.

Zvereva’s singles ranking has dropped to No. 25 and she became known as a doubles specialist, especially this year, mainly because she and partner Gigi Fernandez are shooting for the Grand Slam doubles title.

Zvereva said she simply didn’t look forward to facing the pressure of singles.

“I think I have done enough for my tennis,” she said. “I was No. 6 once. That is enough already. I’d like to be a great player, but I also know how much it takes and that is kind of hard.”

Nothing is harder for Navratilova than to lose in Grand Slams that she once ruled with her steely determination. But now, it’s all rusting.

Right after losing to Sukova, Navratilova said her mind already is working overtime.

“It makes me want to say forget it, I don’t want it anymore, or say, next year definitely is my last year and it also wants me to quit right now,” she said. “All those things go through my head.

“Unfortunately, all of those things go through my head during the match. Which is a problem.”

But with eight players left in the quarterfinal round, Navratilova isn’t one of them for the third time in the last four years.

Who is going to win? Navratilova said she has no idea. It’s not her problem anymore.