With just 10 weeks to go, Floyd Mayweather is rapidly booking the undercard for the Mayweather vs. McGregor superfight ... and he's already got one boxer locked in, TMZ Sports has learned.

We've confirmed super middleweight rising star J'Leon Love will fight on August 26 -- Floyd is still trying to lock in his opponent. 

Love is a member of Floyd's TMT boxing team. He's got a 23-1-1 record. Love also happens to be one of Floyd's good friends. And he dated Blac Chyna back in 2015 (though they never consummated their relationship).

We broke the story ... as part of the negotiations with the UFC, Dana White agreed to let Mayweather book the entire undercard.