Top-level tennis always seemed like so much hard work for Justine Henin, the little David who slew countless Lady Goliaths in an illustrious career she chose to end yesterday, at age 25.

The Belgian will not go for a fourth consecutive title at the French Open, which begins in 10 days. She chose not to try one last time to win Wimbledon - the one Grand Slam that eluded her.

She just said au revoir, simply, yesterday afternoon in a press conference at her new tennis facility in Limelette, Belgium.

"This is the end of a child’s dream," she said, "Maybe people will think I’m still young, but in life there are no rules. I’ve invested enormously in my sport. Since I was five, I’ve only lived for that."

It’s a shocker, no doubt about it. Try to think of an athlete, in any sport, who retired so young, at the top of their game, for no apparent reason other than they had just had enough.

Perhaps the only real comparison would be Bjorn Borg, who was 26 when he inexplicably hung up his wooden Donnays.

The comparison is apt; the Swede was the Ice Man on the outside. But keeping all of the nerves, the pressure and the anxiety away from public view had totally demolished his insides.

Burnout doesn’t happen as often in the men’s game, because guys compete so very differently than girls. We’re just not wired the same; it seems to take more of a toll on us emotionally.

You see it even in the junior ranks. And the girls are so much younger than the boys when they hit the big leagues, they’re wiped out by their mid 20s.

Coincidentally, golfer Annika Sorenstam announced yesterday this will be her last year on the LPGA tour. But Sorenstam turns 38, will marry next January and start a family, and has been at it 15 years. She has also become a corporation, with many off-course pursuits, including course design, to keep her busy.

Henin, whose life has been swallowed whole by her single-minded pursuit of excellence, is not at that point.

But the two have this in common: they leave at the top.

Several tennis players said to me yesterday they thought Henin was retiring because she had been struggling this year - the 6-2, 6-0 whitewashing at the hands of Serena Williams in Miami last month comes to mind.

But that’s not it.

If that were it, Roger Federer would be on the golf course caddying for his pal Tiger right now.

She’s not done because she was struggling; she was struggling because she is done.

Henin needed every drop of emotion, every bit of physical effort, every ounce of desire - and in double quantities - to get the most out of a game in which she often gave up five inches and 50 pounds to her opponents.

With hindsight, all the signs were there. We didn’t see them, because we don’t know what it’s like to be her; we can’t conceive of walking away from all that money and all those accolades.

Henin opened the academy in Belgium last December, and opened another one near Orlando, Florida this year. Her longtime coach/mentor/ father figure/friend Carlos Rodriguez is intimately involved in both.

So now it makes sense; she was setting the table for Rodriguez to be well set up when she left the game - because he’ll never have another Henin.

Her words, both after the loss to Williams and the one 10 days ago in Berlin to Dinara Safina, spoke of a longing to burst outside her bubble in a way she had never admitted before.

She wanted to travel more for fun. She had been thinking about going back to school. She was talking about life after tennis, but it seemed so unfathomable, no one was listening.

She leaves tennis much as Martina Navratilova did, a once-misunderstood champion who had finally revealed enough of herself to get the like of the people, if not their love.

Over the last year, she unloaded a husband she had married too young, a substitute for the family structure she had cast aside for her career. Then, she reconnected with that family.

A more open, human, engaging person emerged from the protective cocoon she had wrapped around herself ever since the death of her mother at age 12. A likable person.

Perhaps Henin  herself also liked that new person, wanted more time to get to know her. She wasn’t going to be able to do it and still stay at the top.

So she left.

And it doesn’t appear there are any regrets. Only relief.

Her game, on the other hand, was always appreciated: the dreamy one-handed backhand, the variety, the thoughtfulness.

The stylists of the women’s game are fading away.

Hingis is gone, Amélie Mauresmo seems destined to follow in Henin’s footsteps soon.

The Maria Sharapova big-babe, ball-bashing clones keep coming, in droves.

Henin will be missed more than she probably thinks.