Floyd Mayweather Jr has teased the prospect of a possible maiden foray into the brutal world of mixed martial arts (MMA) and presumably a prospective rematch against Conor McGregor on unfamiliar territory, insisting he could make $1bn as the result of a mega multi-fight deal with the UFC.

'Money' ended his illustrious career for the second time in August after preserving his formidable unbeaten streak and passing Rocky Marciano's 49-0 record courtesy of a 10th-round stoppage of UFC lightweight champion McGregor in a lucrative cross-code boxing match at T-Mobile Arena in Las Vegas.

However, speculation over another potential return has been circulating in recent weeks, with Mayweather, who will turn 41 in February, said to be "training like a maniac in the gym".

Plenty of fighters - including Britain's Amir Khan - have been quick to call him out, while many consider an eventual second bout with McGregor as inevitable due to the eye-watering financial rewards on offer.

The idea of the vaunted pugilist transferring his dominance into the octagon has always been considered as incredibly unlikely, but Mayweather, who says he was recently approached about ending his latest stint in retirement, claims the option is there for him to add to his enormous fortune with an agreement with the UFC.

"You already know I'm a money-getting m**********r," he responded to comments from fans in an expletive-laden Instagram stream relayed by FightHype.com. "I'm Money May. They just called me not too long ago and asked me to come back. I can come right back.

"If I want to, I can come right back to the UFC. I can go fight in the octagon. I can go and do a three or four fight deal in the octagon and make a billion dollars. Remember, I'm Floyd Money Mayweather and you m***********s love me, and I love you m***********s."

However, discussing his short-lived return to combat sports after a two-year absence earlier in the same stream, Mayweather described MMA as a "barbarian sport".

"I fell out the game for two years and came back," he said. "I kick ass. I'm so tough at what I do, they had to go to a whole other barbarian sport to go get a m**********r to try to f**k with me. You already know what I did with that, lights out, party's over."

A definitive announcement on McGregor's UFC future has yet to be made following his big boxing payday and another of Mayweather's arch-rivals - legendary former eight-division world champion Manny Pacquiao - recently set tongues wagging of another high-profile clash inside the ring. However, those rumours have since been quashed by both UFC president Dana White and Top Rank CEO Bob Arum.

The brash Dubliner is coming under increasing pressure from fellow fighters to finally defend the belt he claimed from Eddie Alvarez on his last MMA appearance 13 months ago. Tony Ferguson has held the title of interim lightweight champion since submitting Kevin Lee at UFC 216 in October and 'El Cucuy' recently called for a 155-pound unification bout to take place in March or April 2018 after he has recovered from minor elbow surgery.

While McGregor is still technically under contract with the UFC, ESPN report that the two sides have held talks over restructuring the deal before he commits to fighting again.

Floyd Mayweather
Could Floyd Mayweather make another comeback in 2018? AFP/Getty Images