Floyd Mayweather Jr. vs. Jose Luis Castillo I (2002)

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.