Floyd Mayweather has been telling people close to him that he's considering a 51st fight -- and he's been training like a maniac in the gym ... but we're told there has been NO official movement ... yet.
Here's the deal ... people close to Floyd say he's still in fighting shape and ready to go. He even posted video training in his Vegas gym. We're told he's been kicking around the idea of another comeback.
The obvious matchup ... a Conor McGregor rematch -- especially with the money they made in the first fight.
We saw Showtime Sports honcho Stephen Espinoza -- a major part of the first fight -- and asked if there was any movement behind the scenes.
Long story short -- nothing happening now ... but Espinoza isn't ruling it out at some point down the line.
Stay tuned ...