All along Las Vegas’s neon-infested Strip, huge billboards declare it “The Fight of a Lifetime” and few in boxing are disagreeing with that, even in a business so often blinded by bullshine.

The long-awaited coupling of Money and Manny this weekend brings an epic collision that in many respects is the biggest-ever happening in the annals of boxing. Even non-fight fans are agog.

The build-up has been unsurpassed and interest phenomenal on both sides the Atlantic while the Philippines, will come to a standstill as the icon worshipped by its entire population of 100 million attempts to be the first to overcome an opponent who unashamedly considers himself the noblest artist of them all.

But is it really the biggest? Or simply the richest?

While there certainly has not been a boxing event of this magnitude in the past 30 years or so, the night Muhammad Ali first fought Joe Frazier at Madison Square Garden in March 1971 remains arguably a huge boxing occasion in terms of global interest because it was a world heavyweight title bout witnessed on terrestrial TV rather than subscription channels.

Episode one of the Ali-Frazier trilogy was the first fight to actually transcend boxing, with its social and economic overtones and a then record purse of $5 million (£3.3 million/€4.6 million). As happening it set the benchmark for the glitz and glamour that envelops the fight game - indeed all major international sport-today.

It was boxing’s first big event, as opposed to a fight. Unlike Mayweather and Pacquiao here were two rivals in their time whose enmity was genuine. Ali’s three years in exile probably cost him his first defeat but the contest at Madison Square Garden was memorable for its intensity, and paved the way for future epics in the ring.

Even Bob Arum, the 82-year-old American octogeniarian impresario who is a co-promoter of Saturday’s (May 2) mega-fight as well as Pacquiao’s manager, admits: "The first Ali-Frazier fight was huge. The world stopped.

“It had one great advantage...Muhammad Ali. I don't think any fight, even from what we call the golden age of [Sugar Ray] Leonard, [Marvin] Hagler, [Roberto] Durán and [Thomas] Hearns, will ever be regarded as big as that one."

I remember it as the night I went for a pee before the fight and found myself standing alongside someone I thought I recognised. ”How ya doing’ fella?” he enquired. It was Frank Sinatra, accredited as a ringside photographer for LIFE magazine.

We were also advised to wear our supplied baseball caps in the press seats because “if a riot breaks out the police will want to know which heads to hit, and which not to hit!”

I have wavered over three Ali fights - the first against Frazier, The Rumble in the Jungle in which he rope-doped and finally toppled the ogre that was George Foreman and finally settled on The Thrilla in Manila as the greatest fight I have ever seen.

In sweltering heat just after breakfast time Ali and Frazier, two giants supposedly past their peak relentlessly battled heavyweight boxing’s war of wars. “It was,” gasped Ali afterwards “the closest thin to dyin’".

He was slumped, exhausted, on his own stool, watching anxiously at the end of 14 blistering rounds as Smokin’ Joe’s compassionate cornerman Eddie Futch instructed his half-blinded man: “Sit down son. It’s all over. But no-one will ever forget what you did here today.” For me this was not only high among boxing’s biggest fights but outstandingly the best.

Unquestionably Mayweather v Pacquiao, a bout the world has drooled over for so long, is fiscally the biggest in boxing history. But fistically? That remains open to argument for this is not so much a fight as an event dominated by escalating egos with diminishing talents.

It is a duel that has been hugely anticipated, perhaps too much so as impatience at them getting it on saw interest dwindling, fans knowing how much better it might have been have been five years ago.

But not having Mayweather and Pacquiao swap blows is like Real Madrid never playing Barcelona, Novak Djokovic never meeting Roger Federer or Sebastian Coe never racing against Steve Ovett.

It is a classic contest of contrasts between arguably the most talented gloved gladiators of the past two decades, though both have seen better days.

The two were hardly spring chickens when it was first mooted in 2009 when they were still in their pugilistic prime. Now, with Mayweather 38 a few weeks ago and Pacquiao 36, they are the ring's Sunshine Boys, though these days boxing can be as much a country for old men as the young.

But at last the coupling that has had a gestation period of elephantine proportions finally becomes a happening. And when Mayweather and Pacquiao now touch gloves at the MGM Grand in Nevada's casino citadel next Saturday night (around 4am on Sunday (May 3) morning here) the cheers will be drowned out not by the jangling sound of fruit machines but cash registers.

The colossal collision for the mantle of the supreme fighter of the modern era has generated $400 million (£261.5 million/€365.6 million) in ticket sales and global TV revenue, with a purse split 60-40 in favour of Mayweather, who will earn in the region of $150 million (£98.1 million/€137.1 million) with Pacquiao guaranteed $100 million (£65.4 million/€91.4 million).

From Mayweather’s gold-flaked gumshield to Pacquiao’s shorts specially lengthened to accommodate more sponsorship, this is an unprecedented array of welterweight wealth with tickets costing from $1,500 (£982/€1,371) to around $11,000 (£7,199/€10,068), with most going to the high rollers, A-list celebs and the otherwise rich and infamous. Some are now being offered on websites up to $128,000 (£84,000/€117,000) .

The Michigan-born Mayweather, full of bling and braggadocio, exudes little bonhomie for a man whose middle name is Joy. But he is the ring’s classic master craftsman, stylishly elusive and defensive, unconquered in 47 bouts through five weight classes stretching back to 1996, when he turned pro after winning an Olympic bronze medal in highly controversial circumstances in Atlanta.

Piqued at believing he was robbed of a gold medal chance, within two years he had acquired his first of 11 world titles in five different weights. Only one man - Oscar de la Hoya has taken him to a majority decision and he has never taken a count.

But his form outside the ring is less palatable. Dating back to 2001, Mayweather has a consistent record of abuse against women, for which he has been arrested or cited seven times. He served a short prison stint in 2012 following a brutalising incident against Josie Harris, his former girlfriend and mother of three of his children.

Admired for his skills rather than appreciated for his narcissistic persona, the ‘Money Man’ now simply labels himself 'TBE' - 'The Best Ever' - unashamedly claiming he is the most gifted practitioner of the fighting arts since Sugar Ray Leonard and better than Muhammad Ali.

There is no such self-aggrandisement about his Filipino rival. Pacquiao, a talented musician and singer is adored in his homeland. Since 2010 he has served as a Congressman in his home province of Sarangani and plans to run for the country’s Presidency in 2016.

The Pacman has been beaten five times in his 64 contests and has had to fight his way back after two defeats in 2012, including a devastating KO by Mexico’s Juan Manuel Márquez.

He has won world titles in six weight divisions and is the current WBO welterweight champion, turning pro as a 16-year-old in 1995 while living on the streets after, the story goes, leaving home when his father killed his pet dog and ate it!

Despite the fact that it may not be the fight it could have been five years ago, it is still boxing's most mouth-watering match up for a generation, a throwback to the halcyon era of the 1970s and 80s, recapturing a glimpse of the sport when natural pairings of skill and will between the ring’s supreme gladiators such as Ali, Frazier, Mike Tyson, Foreman, Larry Holmes, Leonard, Thomas Hearns and Roberto Durán were the norm and not a novelty.

Indeed, outstanding as both have been for a couple of decades it is hard to find a place for either in the post-war pantheon of pugilism alongside those ring legends - especially Ali and Leonard in their prime.

Even in the prolific 147lb welterweight division where Mayweather is defending his WBA and WBC belts, he would just about scrape into my top 10 behind the two Sugar Rays (Robinson and Leonard), Kid Gavilán, Emile Griffith, Oscar de la Hoya, José Nápoles and Hearns.

So the $400 million (£261.7 million/€366.1 million) question. Who wins?

If this is to be an epic confrontation it will be because Pacquiao makes it so. He likes a free-flowing, open fight; Mayweather prefers commanding the centre of the ring, or laying on the ropes, clinching and counter-punching.

On paper it is a compelling contest. In the ring it may be different. “Mayweather can put the fans to sleep the defensive way he fights,” argues one of the great relics of that golden era, Marvin Hagler. ”It could be boring, an anti-climax.”

The majority view among the pros, including that of Ricky Hatton, who fought and lost heavily to both, and Amir Khan, who wants to be the next to fight either, is that Mayweather’s cooler artistry will be the decisive factor. The bookies concur, making him 2-1 favourite.

My own instinct has always been that Mayweather, still a silky, sly master of boxing's backfoot arts, despite looking a tad less sublime of late, would prevail over southpaw Pacquiao's swarming piston-punching aggression. I stick by that.

A purist though no crowd-pleaser, Mayweather is the Chelsea of boxing, boring but effective, but like Mourinho’s men he relentlessly grinds out results.

When the gold dust has settled over the arena I expect flash Floyd to have his hand held up as the winner, possibly by a split decision, with Superfight 11 looming in the autumn as the biggest, richest re-match of all time.