Paul and Woodley are set to face-off in the ring in Cleveland on Aug 29 ... and "The Chosen One" has been in the gym with Floyd leading up to the bout -- something Paul believes he'll regret.

"I think it's a disadvantage for him, actually," Paul says. "Him like hopping around with different coaches, trying to learn different styles. That's not how you progress in this sport."

"Floyd didn't even have a strategy to go in and beat my brother. So, how is he going to tell Tyron what to do?!?"

Paul says the only reason Mayweather's even training TW is because he still feels some type of way about the "gotcha hat" incident ... as well as his jealousy over the YouTube superstar's rising success in boxing.

"He sees what I'm doing in the sport and he wants to put an end to it."

"He's a very greedy guy. He doesn't want anyone to be more popular or more claim than him."

Paul added, "I think he wants to see me lose. He wants to see this whole train get stopped."

But, the 24-year-old says that ain't gonna happen with this fight -- telling us he's gonna give Woodley the Nate Robinson treatment.

"Tyron don't let your kids this man, you're gonna be in the unconscious on the canvas bleeding out!!!"

"I said the same thing to Nate Robinson and I'm gonna say the same thing to you!"