That call out was done through Instagram:
Here is a transcript of what Nurmagomedov said in the above video:
“Hey, let’s go, Floyd. We have to fight now. 50-0 vs. 27-0. Two guys never lose. Let’s go. Why not? Because in the jungle only one king. Only one king. Of course, I am the king because he cannot drop McGregor, but I drop him easily.”
Mayweather would get wind of the call out from the UFC Lightweight Champion and would issue a response of his own through Instagram:
The boxing great has already competed against one popular UFC fighter in the boxing ring, as Mayweather defeated former two division UFC champion Conor McGregor by tenth round TKO in The Money Fight in August of 2017.