Floyd Mayweather has threatened to dish out "the same treatment" to YouTube boxer Logan Paul as he did to Conor McGregor.
Mayweather retired with a stunning 50-0 record in 2017 after stopping UFC crossover star McGregor but has been taunted towards stepping back into the ring with Paul.
"Paul can get the same treatment before I go conquer Japan again," Mayweather posted on social media on Wednesday night.
It was in response to Paul posting a video on social media where he said: "If I caught Floyd in a real fight? I'd whup him. MMA? I'd whup him. The only place Floyd is safe is the boxing ring.
"I would fight Floyd any time, any place. If I caught Floyd with one punch, I would snap him in half.
"I'm eight inches taller, 40lbs heavier, half his age, two times as hunger, 10 times as smart."
After Mayweather's response, Paul hit back "50-1" in reference to giving the boxing great his first loss.
Mayweather took part in an exhibition bout that does not appear on his official record two years ago in Japan - and promptly knocked out 20-year-old kickboxer Tenshin Nasukawa inside one round.
He has repeatedly teased another similar occasion in Japan but, earlier this year, YouTuber Keemstar told his 2.8m Twitter followers that he had inside-information telling him Mayweather would fight Paul.
Paul's professional boxing debut was a loss to fellow YouTuber KSI last year.
KSI's trainer Viddal Riley, who is signed to Mayweather Promotions, has since said about Mayweather vs Paul: "Both guys are in talks. It is not confirmed yet.
"Remember, I get the inside scoop. I hang around the family. It is not confirmed yet but it is in talks."
The legacy (and future) of YouTuber boxing
KSI told Sky Sports: "Of course I would do it again. I'm waiting for the right contract.
"When I was in the Mayweather camp, I spoke to people there. I understand how valuable I am, how in demand I am.
"Fight Jake Paul for less money than I got for fighting Logan? Why would I do that?"