Manny Pacquiao -- Ronda Rousey Could Beat Mayweather

Manny Pacquiao says he honestly believes UFC champ Ronda Rousey could BEAT UP Floyd Mayweather in an MMA fight ... saying, "She's strong enough."

Manny made the comments on "His & Hers" on ESPN -- saying, "She's strong. She's strong enough to beat Floyd Mayweather in MMA."

And Pacman's not the only one who believes it -- Ronda does too!