Floyd Mayweather has fueled rumours he will make a sensational return to fight UFC star Conor McGregor in a boxing match.
The undefeated superstar, who retired from boxing last September, said the fantasy bout was 'possible' and told fans to 'keep your fingers crossed' at a meet and greet in Las Vegas on Saturday.
Mayweather's comments were followed by a tweet from McGregor on Sunday morning, with a mock-up staredown between the two with the tagline MMA vs Boxing.
Speaking ahead of Amir Khan's knockout loss to Saul Alvarez on Saturday night, Mayweather said of the potential bout. 'It's possible you know.
'It was a name that was shot at me but the rumour that ya'll been hearing, is the rumours that I started, may not be a rumour, so keep your fingers crossed.
'It may be a boxer versus an MMA fighter, you just don't know.'
Rumours of a potential bout between the men who command the highest gates in their respective sports began circling on Friday, but Mayweather has said it would take a high price for him to take on the Irishman.
'Well, he already knows my number, I talked about that on the TV the other day. Every time I go out there and compete at the highest level you know my number is of course $100million (£69million) or better.
'I feel that I can demand that because I've broken all records in the sport of boxing.'
McGregor was supposed to headline the milestone UFC 200 card in Las Vegas in July but was removed from the card after a fallout with the promotion over his media obligations.
'The Notorious' and Mayweather have enjoyed an on-and-off war of words, mainly on McGregor's part, over the last year.
The Irishman is the current UFC featherweight champion, fighting most often at 145lbs, while Mayweather's last bout was at welterweight, which has a 147lb limit in boxing.
But while McGregor and Mayweather are both clearly in favour of at least building up interest in the bout, UFC president Dana White doubts the fight would take place.
'McGregor-Mayweather? No,' White told the LA Times on Friday.
'It'd be very hard to pull off. I've heard Floyd is on a worldwide vacation on Mayweather Air spending millions in every country he visits.'