Floyd Mayweather's father says it's not even gonna be close -- "Even if [Conor] goes the distance, [Floyd's] gonna whoop his ass!" 

Floyd Sr. -- who's also TBE's trainer -- sat down with Helen Yee and said they've drawn up a perfect game plan for Conor McGregor and plan on giving him a few "presents" in the ring.

"We gonna be able to touch him up," Floyd Sr. said ... adding Conor's "gonna get whooped."

"If Floyd stops him or not -- it doesn’t make a difference for me. As long as Floyd beats the hell out of him. And that’s what I believe is gonna happen."