Sideline Cut:Las Vegas and boxing make up the most lurid and intoxicating of all the concoctions in sport, and late tonight in the neon jewel on the Nevada desert, the latest biggest show on earth returns. The meeting of Oscar De La Hoya and Floyd "Pretty Boy" Mayweather cannot generate the kind of global excitement of the vintage heavyweight bouts of the previous four decades. But it is an irresistible story.

The famous and moneyed will turn up powdered and smiling at ringside, joined in spirit by departed ringside regulars like Frank Sinatra and Tupac Shakur, gunned down in his car during the height of the Mike Tyson mania, and the celebrated press columnists like Arthur Daley or Jimmy Cannon, who often despaired of the fighters they covered but still always turned up, and the forgotten ball-players and starlets and divas and actors and other ephemeral celebrities who have stopped for the flashbulbs down the years on the way into the greatest fight of the day.

Tonight will be another spin on that time-honoured gaudy and godless carousel, only the names and the fashions and the ticket prices changing, with $22,000 bandied about as the asking price for those with enough pull to even pay for a seat.

Prizefighting is an unashamedly decadent business and there is surely an absurdity that the cream of show business don their best threads and diamonds to sit and watch men pounding the meat and heart out of one another, men prepared to hurt and conceivably kill one another in the name of honour, sport and entertainment. It is simply a scaled-down version of the thrill and blood-lust that used to ring around the infamous Roman coliseum. The plush toyland facade of Vegas, the attendance of Hollywood's latest flames, the gentlemanly etiquette of evening dress - all help to gloss over the primitive truth and controlled violence that makes boxing the disturbing fascination it is.

As usual, tomorrow morning's fight has been billed as a classic morality play, the dignified champion in one corner staring down the brash, mouthy challenger. It is one of the oldest boxing stories. Still, nobody with an ounce of human curiosity could fail to be drawn to this crossing point of Mayweather and De La Hoya.

Even classy boxers can disappear overnight, and that is why it seems De la Hoya has been around forever. It is astonishing to think he first burst to prominence in that distant Olympic summer when Michael Carruth brought glory to this island. De La Hoya also claimed gold as a featherweight in Barcelona back in 1992 and quickly latched on to the sobriquet of Golden Boy after what was a lean Games for US boxers. Since then, he has won belts in six weight divisions, become a folk hero among American Hispanics and, most admirably of all, is poised to become the key player in future fight nights through his Golden Boy Promotions company.

He is charming and likeable and careful to market his chiselled, clean-cut features, which helps explain why De La Hoya's is one of the most heartening stories from a culture that forgets about its heroes once their punching power wanes.

It could well be that Mayweather will also get out of the fight game with his health and fortune intact. The mouthy younger man has battled his way up from the wrong side of the tracks, his mother strung out on street drugs and hopelessness and his father, Floyd senior, caught up in small-time criminality.

The elder Mayweather was himself a good-enough boxer to have earned ring time with Sugar Ray Leonard - another shrewd survivor in the business of boxing - and he rehabilitated himself as a trainer, intermittently training his son but making his name while working in De La Hoya's corner for the past five years. But for a disagreement over purse percentages, tonight's fight might have had the additional intrigue of a partly estranged father watching his fighter boxing for a world title against his son.

As it happens, Mayweather senior will attend the fight courtesy of De La Hoya, who set aside four ringside tickets for his former adviser, with the scathing remark he "thought his son would take him to the fight". The younger Mayweather's response was typically ebullient and provocative: "That ain't nothing. Whoop-de-do."

Mayweather junior's remarks have been nothing like as offensive as Mike Tyson's but he is happy to play the anti-hero in this fight, vowing to destroy the older man and taunting him during relentless promotional engagements. His attitude is that of the archetypal angry young man owing the world nothing. And though his rise from a childhood of suburban impoverishment to the stardusted nights of professional boxing is the stuff of the American dream, we can only guess at the loneliness and the pain he has overcome in the past 20 years.

Mayweather is the pantomime bad guy in the ring tonight, with conservatives and sentimentalists bound to root for the more polished and moderate and older De La Hoya. The businessman in De La Hoya can happily take the insults: it is his stated ambition to break pay-per-view records with this fight. He may well do it.

And it is fascinating to think of this elemental contest, the image of these tough, street-smart survivors with quicksilver hands and lion hearts, flickering on televisions across South America, Europe even Africa, equally compelling to those dwelling in palaces as to those crowded in downtrodden neighbourhoods.

Boxing's reputation has become tattered in recent years, its flagship heavyweight division no longer capturing the popular imagination. The revival of interest in Muhammad Ali over the past 10 years has proven that. There are few people now who do not recognise Ali's famous interview material or the iconic footage of his morning roadside runs in Kinshasa in the same way as we recognise a classic comedy sketch or great moment in film. Others, like Ali's nemesis Sonny Liston, gradually fade into obscurity.

An old Newsweek magazine report described Sonny's pre-fight training routine: "Liston fortifies himself with two meals a day (five strips of bacon, three soft-boiled eggs, two glasses of fruit juice, and two cups of tea for breakfast: two pounds of steak for dinner), walks seven miles in seven-pound shoes, shadow boxes four rounds and skips rope nine minutes to a jazz recording of The Night Train."

Now, that skipping routine would be something to see on film. But Liston, flawed and malevolent in some respects but kindly in others, never had the face or manner or wisdom to win public hearts, and his demise was about as lonely as it gets.

Not far from where Liston lies beneath his existentially simple headstone, Mayweather and De La Hoya will go at it under the bright lights, spurred on by the beautiful people.

But whoever wins the fight, there is the sense both men will walk away from a sport littered with wrecked lives knowing they have already provided for their futures.

And even if the fight does not make the grade as one of the epochal encounters, it does not matter. Under the shade of darkness it will be, for one glittering night anyway, the only show on earth.