What she lacks in power, she makes up for in cunning. Agnieszka Radwanska, 22, relies on tactical accuracy and her understanding of geometry to outfox her opponents, skills that have drawn comparisons to Martina Hingis. As early as 2006, when she was just 17, Radwanska began to upset top players, including Venus Williams. By 2008, she had defeated Svetlana Kuznetsova and Maria Sharapova and had clawed her way into the top 10. That year she became the first Polish player to earn more than $1 million in prize money. By mid-2011, she had earned more than $5 million.