Floyd Mayweather has claimed he has offered UFC star Conor McGregor $15m (£12m) to face him in the ring.
The two have been linked with a super-fight for some time, although a deal has yet to be struck.
But undefeated boxer Mayweather, who has not fought since September 2015, has thrown down the gauntlet to Irishman McGregor in a bid to try and force his hand.
"Conor McGregor keeps telling everybody he wants the fight," Mayweather told ESPN's First Take. "Let's make it happen.
"We tried to make the McGregor fight. My number was a guaranteed $100m (£83m). We offered him $15m (£12m).
"We're the A-side and I don't know how much he has made but I'm pretty sure he hasn't made $2m (£1.65m) in an MMA bout.
"We can talk about splitting the PPV (pay-per-view) but we are the A-side.
"How can a guy talk about $20m (£16.5m) or $30m (£24.7m) if he's not made eight or nine? Is the fight going to happen? We're working on it."
McGregor - currently taking a break from mixed martial arts as he prepares to become a father for the first time - took to social media later on Wednesday with his reaction to Mayweather.
The 28-year-old posted a picture on Twitter of himself standing over the fallen figure, wearing one boxing belt and holding aloft two others.