If it were possible to debase professional boxing more than some damaged, overage fighters have repeatedly done, you can bet on Las Vegas putting it on.

Saturday night in the gaudy Vegas Strip on what they call Paradise, Nevada pushes the boundaries. If you haven't heard, you are not living on this planet.

Every media portal is engaged in milking every last pay-per-view dollar out of anyone daft enough to put his or her hard-earned cash into viewing the peep show between Floyd Mayweather Jr and Conor McGregor.

Social media has been turned blue with the profanities between both fighters. McGregor first broached the possibility of fighting Mayweather, who retired unbeaten in September 2015 with a 49-0 record across four weight divisions, in July 2015 while appearing on TV host Conan O'Brien's talk show.

Mayweather followed suit by fanning the flames, insisting he would return to the squared circle only for McGregor.

Financial woes could also have been behind Mayweather's comeback with various media outlets including The New York Times reporting that the US Internal Revenue Service still has Mayweather on the hook for US$7.2 million (S$9.7 million) in taxes from 2010, on top of the US$22.2 million he owes in 2015 taxes - the year he earned US$200 million to fight Filipino Manny Pacquiao.

The Irishman has never boxed as a professional. He is a fighting man, but in mixed martial arts (MMA), which certainly do not observe the rules drawn up for fist fighting that were endorsed by the Marquess of Queensberry 150 years ago.

No sir. In McGregor's game, anything goes, inside a cage not a ring.

"A part of me can't wait to get back to kicking people, to elbowing them in the head and all the rest of it without the restraint of rules," the Irishman said this week.

"In the end, I'm fighting a man who just loves fighting."

Actually, that is open to question. Mayweather's aim is not to get hit. You might remember his previous ballyhooed showdown on the Strip against Pacquiao two years ago?

Pacquiao couldn't, or didn't, land a meaningful punch on the defensive master Mayweather. He later claimed that was because of a shoulder injury he had hidden pre-fight, suggesting that he had gone in against the American handicapped, with his right hand virtually unusable.

He couldn't tell anyone, of course, because that would have called the bout into question. And given the game away on all those who paid top dollar to be ringside, or the millions induced to bet on the fight worldwide.

The bookmakers are working as hard as the fighters on Mayweather's one night only return out of retirement.

Since the fight will be governed by boxing rules, and therefore overwhelmingly stacked in Mayweather's favour, punters would at one time have had to lay out US$33 to win just US$1.

That should have made it a fool's bet, a closed book. Not a bit of it.

The bookies will take your money on anything from which of the 12 rounds this might end to if (probably when) McGregor attempts the first kick. Or some other infringement.

If you believe the hype, over 95 per cent of bets being laid are on McGregor.

He's a fighter, remember, against a retired fighter. Mayweather is 40, while the 29-year-old comes from a different sphere of prize fighting.

They both stand just short of 1.75m. They are of similar weight, and roughly the same reach though McGregor's leading hand is his left - a southpaw in boxing parlance.

But what is being promoted as the world's first billion-dollar 12-rounder is an impostor. Between the insults and the swear words that both men spat out for months to drum up box office numbers, McGregor claimed:

"The name 'McGregor' is steeped in warrior folklore. The Irish passion for fighting comes from a long history of battle.

"I know my ancestors and my bloodline is on the battlefield. They were doing it riding a horse, with a sword, swinging an axe. I'm doing it in the Octagon."

Not this weekend. The arena is a boxing ring. The rules are fists only, and there is a referee to enforce them.

McGregor's countrymen and women (his mother Margaret is his biggest fan) will have to pay up to watch at 2am, Ireland time (9am, Singapore time), on Sunday morning for the start of it.

"You will get some haters," says Margaret. "But I think he gives a lot of people hope. He is everything you see, he's honest and he says it how it is.

"He'd probably kill me for saying this, but he's a mummy's boy."

Sure he is. Straight out of school, he tried his hand at becoming a plumber, but he quit the apprenticeship and lived on dole money instead.

He worked off his energy at the Crumlin Boxing Club in Dublin. Initially fighting for a few hundred British pounds, he worked his way up to become the world champion in two weight categories of the Ultimate Fighting Championship.

Mayweather hankers to beat Rocky Marciano's record. He could never, of course, have gone toe to toe with the world heavyweight champion that was Marciano. Even in boxing, there are rules and limits, and putting a man of Mayweather's physique in against a beast of the heavyweight division would never be licensed.

What bugs Mayweather is that he is unbeaten on 49 wins. Marciano, who died in 1969, remains 49-0.

Some will say that the "crossover" contest against an MMA fighter who is forbidden to use all the tricks (and kicks) of his trade must not be counted in the boxing annals.

Do not bet against it. In fact, if it is not too late, do not bet on anything to do with this freak show in "Paradise".