Floyd Mayweather Jr offered to give Logan Paul "the same treatment" Conor McGregor received after the YouTuber called out the boxing great.
Paul, who has 22.6 million YouTube subscribers, lost to fellow streamer KSI on his professional boxing bow in November 2019.
But that has not stopped the 25-year-old from calling out 50-0 Mayweather.
"I would fight Floyd any time, any place," Paul said. "If I caught Floyd with one punch, I would snap him in half.
"I'm eight inches taller, 40 pounds heavier, half his age, two times as hungry, 10 times as smart."
Mayweather, 43, responded on Twitter and wrote: "These YouTube girls better find some Barbie dolls to play with cause I'm not the one for the kid games.
"3 years ago a fighter from the UFC said my name and I had to put a muzzle on that b****.
"@loganpaul can get the same treatment before I go conquer Japan again."
Paul shared the post and replied: "50-1".
Mayweather was referring to his 2017 defeat of mixed martial arts superstar McGregor.
The Irishman was the UFC lightweight champion but could not back up his big talk against Mayweather in the boxing ring, losing by TKO in the 10th round.
Mayweather has not fought competitively since, although he defeated RIZIN star Tenshin Nasukawa in brutal fashion in a 2018 exhibition in Tokyo.