Within the last month, Bjorn Borg, Jack Nicklaus and Muhammad Ali -- each of whom may, in time, be seen as "The Greatest" in the history of his individual sport -- have brought themselves again to center stage.

Borg says quietly, "I want to be the greatest ever."

Ali desperately yells, "I am still the greatest."

And Nicklaus says nothing, certain that others will.

These larger-than-life world athletes, all uniquely in sync with the psychic needs of their games, encourage us to rethink their place in the century-long history of their sports.

And, since they have so thoroughly dominated their own arenas, to compare them with their only equals -- each other.

borg and Nicklaus have caught our eyes, once more, by winning the most prestigious prizes in their games. Borg now has five consecutive Wimbledon tennis titles, while Nicklaus has four U.S. Opens in golf. No one has ever won those events more often.

Both won, of course, amidst the dignified tinkle of crystal and silver. Yet both were under the greatest strain of their careers -- Nicklaus, because he was 40 and had self-doubts; Borg, because the weight of his five-year streak redoubled the tension of, perhaps, the tautest five-set final in Wimbledon history.

As befits the grime and crime of boxing, Ali has demanded our attention with indignity, making a public buffoon of himself before the Duran-Leonard fight and after the Holmes-LeDoux farce.

Beneath all their dissimilarities, this trio has a large link in common. Just a month ago, all three were -- in very different ways -- on a tightrope.

Each knew that what he did in the near future might determine his final place in the pantheon of his sport.

Nicklaus told friends all spring how dearly he would love one "great comeback" -- a romantic, almost sentimental victory -- to crown a career of crushingly efficient wins.

Ali, fixated on becoming "quadruple" or "quintuple" champion (or whatever it is) thinks he has spotted another overhyped mountebank he can puncture to his greater glory -- this time his former sparring partner, Larry Holmes.

After making a career of seeing the faint heart or the feeble mind behind Sonny Liston' scowl, George Foreman's physique and Leon Spinks' dumb courage, Ali can perhaps be forgiven for smelling easy millions behind Homes' please-don't-hit-me-in-my-face jab.

Even the young Borg knows he must play with a sense of no-time-to-lose urgency. Tennis history is full of ephemeral short-lived champions whose fall from being world-beaters to also-rans was sudden, total and unexpected. Ashe and Connors all carry a similar message: once you slip, the climb up the ladder of the "greats" may well be over.

In his short reign since '76 as King Bjorn I, the Swede may have reached, and even passed, the high plateau of Budge and Kramer. Perhaps he is now at the high, cold tree line with Gonzales and Laver, with the peak called Tilden finally in sight.

Rank them how you will, one thing is apparent about tennis greats: they each have their well-defined eras, their periods when they define, and even change the game, whether it be Kramer's serve-and-volley or Borg's back-court topspin ground strokes.

In tennis, glory is often all or nothing. Tilden won six U.S. championships in a row (1920-'25) and two Wimbeldons in the same period. Gonzales was pro champion eight years in a row ('54-'61). Eat everybody while you can, because the next young fuzzy-ball shark -- trained from adolescense just to defeat your style of game -- will come soon enough.

The sort of comeback in athletic middle-age of which Nicklaus and Ali can dream is largely forbidden to Borg. He must maintain, keep the streak going, constantly reassert his slim edge, because, as Chris Evert Lloyd has found, the way all the way back is precarious.

So, despite their different ages, Borg, Ali and Nicklaus must all operate on the same assumption: don't save anything for tomorrow, since there may not be one.

Of the three, Nicklaus has taken the most dramatic and perhaps conclusive step on his quest.

His record-setting victory at Raltusrol, tinged with sentiment as well as excellence, may have pushed the Nicklaus legend past that of Bobby Jones and Ben Hogan, those other modern four-time Open winners.

A mere compilation of wins might not have been enough, some time in the 21st century, to place Nicklaus' tempered power, his middle-brow stability ahead of Jones' elitist, intellectual, simon-pure-amateur snob appeal.

Now, like Hogan after his return from a car wreck in the '50 Open, Nicklaus seems more human, more appealing, thanks to his new fallibility. Even 18 major championships spread over four decades, stretching back to the U.S. Amateur of '59, can use a dash of schmaltz.

Where tennis greatness is usually proven by one sustained stretch of dominance in a player's prime, golf supermacy is a series of intermittent battles and temporary victories over the game itself, rather than a particular foe.

The best tennis player of the day wins with far greater frequency than the best golfer. A five-set, four-hour Wimbledon match is a bit like watching two NBA guards play one-on-one to 500 baskets. You're going to see the same "moves" ad infinitum. But you're also going to find out who's better.Golf is far more indeterminate.

The accomplishments of Borg and Nicklaus are of similar stature, yet incomparable. Nicklaus couldn't win the U.S. Open five years running, as Borg did at Wimbledon. It's not in the nature of the game. And Borg almost certainly won't win Wimbledon in three different decades -- 18 years apart -- as Nicklaus won the Open in '62, '67, '72 and '80. That's not in the nature of his game.

And perhaps, to come full circle, that is the source of the morbid fascination of watching Muhammad Ali so determined to prove that none of the normal standards of sport apply to him. Perhaps a golfer can win the Open in 1962 and 1980, as Nicklaus did. But can a boxer win the heavy-weight title in those same years, which is what Ali keeps saying he is going to do?

At the brawl in Montreal, Ali created the impression that he was a muttering, punch-drunk shell of himself. On national TV this Monday, Ali, with his shirttail out, was sticking his face into the camera like an attention-starved child.

Few public figures have operated so long, and so lucratively, on the assumption that you can never underestimate the public's taste.

Whatever the true state of Ali's mind and motives, he has paid a bitter price in order not to lose the aura that surrounds those few athletes who really can dominate an entire sport.

Today, Borg and Nicklaus seem like the finest of champions -- poised, self-possessed and cloaked in their latest regal robes. Time, and the public's judgment, will be kind to them.

Ali, if he continues to try to trick the public instead of trust their memory of him, may not be so lucky.