Floyd Mayweather Jr. Challenges Manny Pacquiao ... Again

Floyd Mayweather Jr. just issued the challenge the world has been waiting for -- demanding Manny Pacquiao fight him once and for all ... May 5th in Vegas.

As we reported, Floyd's jail sentence was postponed to June so he could fight at the MGM Grand on May 5th -- but so far, his opponent hasn't been determined.

Fight fans have been clamoring for Mayweather-Pacquiao for years -- and now Floyd himself is calling out Manny with the message, "Manny Pacquiao I'm calling you out let's fight May 5th and give the world what they want to see."

Floyd sounded off in the tough and hardcore forums of Twitter and Facebook -- and punctuated his challenge with, "Step up Punk."