One of Floyd Mayweather's TMT members tells TMZ Sports ... he's courting Nate Diaz to walk out with Floyd for the McGregor fight -- and says there's a REAL chance it will happen. 

The man with the plan is "Love & Hip Hop" star, Jason Lee -- who's so close with Floyd, he was part of the boxer's entourage during the McGregor news conference in London. 

Lee also happens to be from Stockton, CA -- home of Nate Diaz -- and says he's making a serious run to get Nate to be a special TMT VIP for the fight ... to essentially troll Conor. 

We also asked Lee if Justin Bieber would be in Floyd's corner for the fight -- since he has been in the past -- but it sounds like JB is taking some time away from TMT to focus on Jesus