US swimmer Michael Phelps kisses his gold medal after winning the men's 4x100 medley relay final during the swimming event at the London 2012 Olympic Games on August 4, 2012 in London. Phelps brought his Olympic swimming career to a close in style, winning a record 18th gold medal as the United States stormed to victory in the 4x100m medley relay. AFP PHOTO / FABRICE COFFRINI        (Photo credit should read FABRICE COFFRINI/AFP/GettyImages)