Boxer Floyd Mayweather has told UFC fighter Khabib Nurmagomedov to "come into my world" and make a bout happen that he believes will earn him more than his fight with Conor McGregor.
The American, 41, beat McGregor in August 2017 in a fight that generated more than $900 million and earned him $420 million.
Nurmagomedov, after defeating the Irishman on his return to UFC, then called out Mayweather himself.
"When I face Khabib, of course I am getting a nine-figure payday," he said.
"More than the McGregor fight. Probably $US100m more - I'm going to say between $US110m and $US200m (more) guaranteed."
Nurmagomedov, 30, extended his unbeaten mixed martial arts record to 27-0 with his 6 October victory against McGregor, but former five-weight world champion Mayweather (50-0) says any bout between the two will happen in the boxing ring.
"We fighting," he told TMZ. "I'm my own boss, so I can't say what's going on at Khabib's end, but at my end we can make it happen.
"I'm Floyd Mayweather. I'm the A-side, you call me out you come into my world.
"I don't know no other fighter that has done the numbers I have done. I don't know any fighters that have made the money I have made, so he called me out - come into my world, make it happen."
However, Mayweather warned the Russian there must be no repeat of the melee that followed his defeat of McGregor in Las Vegas.
"Of course we know Vegas is the fighting capital, and after the fight you have to conduct yourself like a true professional," said Mayweather.
"Not just in the ring, but outside the ring also - you must conduct yourself like a professional."