sentences:  On May 4, 2013 in a fight billed as "May Day"', Guerrero lost to Floyd Mayweather Jr. (43-0, 26 KOs) in the WBC Welterweight Championship fight by a unanimous decision in front of a 15,880 crowd at the MGM Grand arena, with all judges scoring the fight 117-111 in favor of Mayweather.Guerrero won the first 3 rounds, then Mayweather adjusted back to his defensive style and won from the 4th to 12th round.Mayweather landing a high 60 percent of his power punches, which included 23 of 30 power punches in the eighth round, when Guerrero was cut over his left eye.