Juan Martin del Potro (Argentina) Tennis, 21
Argentina's young prodigy Juan Martin del Potro beat Roger Federer, the dominant tennis player of the decade, in five sets at the US Open in September to win his first ever Grand Slam title. It was Federer’s first defeat at the US Open since 2003 and del Potro showed remarkable resilience coming back to win from two sets and a service break down in the third. On his way to the final, del Potro also beat Rafael Nadal in straight sets. An attacking baseline player with a powerful serve and an excellent forehand capable of generating speeds of more than 100mph, del Potro also finished as runner-up to Nikolai Davydenko in the ATP Finals.