NEW YORK -- For tennis players, like Gabriela Sabatini and Andre Agassi, who are 20, and Pete Sampras, who is 19, everything is in the aging.

You start your career with an enthusiasm bordering on monomania. By the age of 14, or 12 for a girl, you are as much a beast of professional burden as any medical intern. Like it or not, either your mom or dad is an Nth degree stage parent. So your earliest memories are of topspin ground strokes and high-kick second serves.

Then, as you approach the peak of the sport, as you begin to fail on world stages like the All England Club, Roland Garros or Louis Armstrong Stadium, you realize -- or are told -- that poise, perspective, almost a kind of athletic wisdom -- are the keys to taking the final steps. You have the shots, the young legs and the match experience to be great. But you must learn to manage your psyche and manipulate your own emotions in moments of crisis like some Himalayan guru.

It's not enough to have sincere feelings, human responses. You must have a fully functional competitive soul, whether that happens to be what's best for you off the court or not.

So, perhaps before you can vote, you must blend your joy and fervor to a maturity far beyond your years. When the President of the United States calls to wish you well, as he called Agassi on Friday night, you can't think about it too much. When the multimillion dollar endorsement contracts arrive, as they did for Sabatini years ago, you can't let it go to your head. When the beautiful people want to party for days on end, you have to go practice. When your parents drive you crazy, treating you like you're still a child, you must be the adult and see them clearly and generously as victims of their own obsessive love for your career.

That's how you get to the top -- the place where Sabatini arrived today by beating Steffi Graf, 6-2, 7-6 (7-4) in the final of the U.S. Open. And it's the pinnacle that either Agassi or Sampras will achieve on Sunday when they meet in the men's final.

How strange it must be for these victors to look at the people whom they defeated today -- great champions all.


Because the aging process does not stop once you have won Wimbledom or the U.S. Open. Then, you must stay at the top -- knowing that the legal limit for dominance or your sport is about five years. (A handful of exceptions per century are allowed.)

On the way to the top, tennis is everything. Once you've won Wimbledon three times, like Becker, or captured the Grand Slam, like Graf, or been ranked No. 1 in the world year after year, like John McEnroe, you must face the next great dilemma -- the melancholy of all things completed, a philosopher called it. Peggy Lee just said, "Is that all there is to a fire?"

McEnroe hit that wall in 1984, the last time he reached a Grand Slam final. Tennis wasn't enough -- as it shouldn't be. He had to marry Tatum O'Neal and have a family. He had to psychoanalyze his temper tantrums and self-destructive actions from 17 different angles, trying to figure out who he should be when he grew up. Now, at 31, he still seems not to own a clear idea.

Graf, 21, and Becker, 22, the West German mega-celebrities, are even more extreme cases. Both have been troubled this year by -- what term shall we use for the problem? -- oh, yes, it's called life. Graf's father was linked with a young nude model. And the German tabloids didn't miss a sin.

As for Becker, he's tired a bit of the pressures of trying to be No. 1 and isn't always distressed when he loses a tough match like his four-set defeat to Agassi. He's sportsmanlike. Which is to say, no longer maniacally driven. This is to say, at a distinct disadvantage against Agassi.

Becker has also learned to appreciate things outside tennis. He can quote Goethe, would like to save the whales, end nuclear proliferation, fight the corruptions of a materialistic age, slow down German reunification and. . . . (For further details, see McEnroe's life story 10 years ago when he turned down million-dollar deals to play in South Africa and played guitar with whatever rock group happened to be the outrage of the day.)

They arrive so young, their primes are so short and their ability to stay near the top thereafter is so difficult, that you sometimes want to pat their little multimillion dollar heads.

After her defeat to Sabatini this afternoon -- in which she reacted slowly, played passively and never escaped a private funk -- Graf looked like Garbo when she heard that Count Vronsky was in real bad health.

"Today I had for nothing a feeling," said Graf. "I have played some good matches this year, and then so bad today.

"In the second set (at 4-5) I said to myself, 'Come on, try. Hit it a little harder.' And it worked for a while."

While Graf might as well have been a poster child for manic depression, Becker was philosophical to the point of being disingenuous. He said his performance was stronger than his win here over Ivan Lendl last year. "I was good, he was great," said Becker.

Tennis is a weird, warped world for those who play it. You hit high gear at puberty, reach your peak between the time you can buy your first beer and cast your first vote. And, except for a few lucky Martinas, Chrissies and Jimbos, you have to guard with all your soul against burnout -- or new trends in playing style -- before you are 25.

"It's all a frame of mind," said Agassi who, a year ago, was seldom given credit for having a mind to put into a frame.

A year ago, Agassi said, he could never have lost the first set to a legend like Becker and come back to win. "It's just natural," he said, "just growing up."