Floyd Mayweather Jr. vs. Victoriano Sosa was a professional boxing match contested on April 19, 2003 for the WBC and The Ring lightweight titles.

[1] Having moved up to lightweight and then defeated José Luis Castillo twice in 2002 to capture his second world title, Floyd Mayweather Jr.'s first defense of 2003 was announced to be against little-known Victoriano Sosa.

Sosa was ranked as the number-five lightweight contender by the WBC, but had seldom fought outside his native Dominican Republic and lost his only other title fight to IBF champion Paul Spadafora.

Before settling on Sosa, Mayweather's promoter Bob Arum had attempted to pit Mayweather against Spadafora in a unification bout tentatively set to take place in New York City's Madison Square Garden, but Spadafora turned down a reported $1,000,000 offer to pursue another unification bout with Leonard Doroftei.

[3] Mayweather cruised to an easy victory, winning lopsidedly by unanimous decision.