Floyd Maywather Jr., Robert “The Ghost” Guerrero, Abner Mares and Daniel Ponce De Leon all tested negative for banned substances following their respective fights this past Saturday at MGM Grand in Las Vegas, said Keith Kizer, executive director for the Nevada State Athletic Commission.

Mayweather retained his welterweight title with a unanimous decision over Guerrero. Mares took De Leon’s featherweight title by stopping him in the ninth round.