The most debated fight in Floyd Mayweather Jr.'s undefeated career is unquestionably his first bout with Jose Luis Castillo on April 20, 2002. Mayweather was 27-0 and moving up to 135 pounds for the first time, where Castillo (45-4-1, 41 KO at the time) held the WBC's title.

Floyd Mayweather Jr. vs. Jose Luis Castillo I

On December 7th, 2002 Floyd Mayweather faced Jose Luis Castillo for a second time at Mandalay Bay Resort & Casino in Las Vegas for WBC World lightweight titles resulting in a unamimous decision win for Mayweather.