Undefeated boxer Floyd Mayweather Jr. (L) of the US and UFC lightweight champion Conor McGregor of Ireland pose during their official weigh-in at T-Mobile Arena in Las Vegas, Nevada, US, August 25, 2017. REUTERS/Steve Marcus

LAS VEGAS: The showdown between undefeated boxer Floyd Mayweather and mixed martial arts champion Conor McGregor on Saturday may be poised to become the richest fight of all-time but despite the hype had yet to generate a sellout.

Just hours before the fighters were to step into the ring, the T-Mobile Arena website had tickets available in every section except one in the upper bowl and the floor with prices ranging from $2,500 to $10,000 for ringside.

While Sin City was buzzing with anticipation on a sizzling hot Saturday, ticket prices have proven too much for the taste of McGregor fans, many of whom are young millennials who grew up watching UFC, not boxing.

The big price tag, however, has not stopped legions of Irishman?s supporters from flooding into the US gambling capital for an event that has also caught the attention of A-list celebrities and high-rollers.

The party shifted into high gear after Friday?s weigh-in as thousands of fans, many wearing emerald green or wrapped in Irish flags, spilt from the arena on to the Strip for a night of booze-fueled revelry that carried on into Saturday.

?We?ve no tickets, said one young fan in his twenties wearing a green Irish soccer shirt and drinking a beer in the hot sunshine.

?We?re going to hit the black jack table and see if we can win enough money to buy some.?

While T-Mobile Arena might not sell out months of hype and a profanity laced world tour to drum up interest in the bout has promoters predicting the fight will surpass the 2015 Mayweather v Manny Pacquiao title bout in 2015 as the biggest pay-per-view event of all-time.

McGregor, who will be making his professional boxing debut, is according to reports guaranteed a $30 million payday that could reach $100 million while Mayweather (49-0) could pocket as much as $200 million.

Gamblers are also looking to cash in.

McGregor, who was on social welfare from the Irish government as recently as four years ago, is the blue collar populist champion but the bulk of the money being wagered is all in Mayweather?s corner.

Smaller bets are going on McGregor with UFC fans backing up their loyalty with their wallets.

But the Las Vegas smart money is all streaming towards Mayweather with reports of several $1 million bets being laid on the "Money Man".

"Fifty and oh! Fifty and oh!" shouted one Mayweather fan, trying to drown out the "Olés!" and chants of "There's only one Conor McGregor!" from the green-clad hordes of Irish fans.

"One punch! one punch!" he said. "Floyd been fighting all his life man, and ain't nobody can get close to him."