Legendary former four-weight world champion Juan Manuel Marquez has added his voice to the growing chorus of boxers past and present to pour scorn on a potential bout between former opponent Floyd Mayweather Jr and UFC superstar Conor McGregor, describing such a fight as an "insult for sport".

Seemingly not a day passes at the moment without a flurry of updated speculation and public back and forth regarding a lucrative cross-sport contest that would be worth approximately $100m for each fighter, with the undefeated Mayweather, who stepped away from the ring after his record-equalling 49th successive professional win over Andre Berto in September 2015, announcing during the Liverpool leg of his UK tour that he was "coming out of retirement just to face McGregor".

He also stated that he did not want to hear anymore "excuses about the money, about the UFC" and urged McGregor to sign up for a June date.

FloCombat subsequently claimed that the 20,000-capacity T-Mobile Arena in Las Vegas, the location for featherweight champion McGregor's revenge victory over Nate Diaz at UFC 202, had put 10 June on hold for the prospective super-fight.

Despite McGregor's obvious prowess in the octagon and formidable striking skills, there are not many who believe that he stands much of a chance of defeating a master craftsman of Mayweather's ilk in a pure boxing match. Already decried as a "joke" by compatriot Saul "Canelo" Alvarez and an embarrassment by Oscar De La Hoya, Marquez has become the latest pugilist to express his opposition to the idea.

"It is an insult for sport, for boxing, and for UFC," the Mexican, yet to call it a day despite having not fought since a 2014 defeat of Mike Alvarado, was quoted as saying by AS. "Every sport deserves respect. In this case, it is boxing and MMA that deserve it."

The 43-year-old, bested by Mayweather upon 'Money's' return from a 21-month absence in 2009, added: "You can't do a fight like this. It's like putting a boxer against a footballer, or a basketball player, or vice versa, it's impossible".

While those aforementioned developments have given further rise to the belief that a fight between Mayweather and McGregor is now a real possibility rather than merely a transparent publicity stint, dismissive UFC president Dana White insists there are no specific dates on the table.

"There is no target date whatsoever," he told TMZ.