Maria Sharapova is a professional tennis player who has won five Grand Slam singles titles and is an Olympic medalist. She is one of the most successful and highest-paid female athletes in the world, having been ranked world No. 1 in singles by the Women's Tennis Association on five separate occasions. Sharapova is also a former world No. 1 in doubles and has won the WTA Tour Championships twice. She is the only Russian player to have held the top ranking in both singles and doubles simultaneously.