Floyd Mayweather vs. Juan Manuel Márquez, billed as Number One/Número Uno, was a welterweight superfight which took place on September 19, 2009, at the MGM Grand Arena in Las Vegas between five-division world champion Floyd Mayweather Jr. (39–0, 25 KO) and three-division champion Juan Manuel Márquez (50–4–1, 37 KO). The fight served as a return to the ring for Mayweather, who, after his knock out victory of Ricky Hatton in December 2007, announced he would take a two-year layoff from boxing which later turned into retirement.