Maria Sharapova has signed a big contract with Nike. She'll be doing an ad wearing a Nike tennis dress where everyone around her will be singing "I feel pretty".

Sharapova, 19, is the highest-paid female athlete when it comes to advertising endorsements. She'll be making about $20 million this year from deals with Nike, Colgate-Palmolive, Tag Heuer, Motorola, Parlux, Sega and Land Rover.