The French Open

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Li Na from China, drinks water during a training session for the French Open tennis tournament, at the Roland Garros stadium in Paris, Saturday, May 24, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)

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Spain's Rafael Nadal, right, listens to his coach and uncle Toni Nadal during a training session for the French Open tennis tournament, at the Roland Garros stadium in Paris, Saturday, May 24, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)

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Spain's Rafael Nadal, returns the ball while his coach and uncle Toni Nadal looks on during a training session for the French Open tennis tournament, at the Roland Garros stadium in Paris, Saturday, May 24, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)

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Novak Djokovic, of Serbia, looks at the balls on his racket during a training session for the French Open tennis tournament, at the Roland Garros stadium in Paris, Saturday, May 24, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)

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Youths sit next to the statue of French tennis legend Henri Coche during a training sessions and qualifying matches for the French Open tennis tournament, at the Roland Garros stadium in Paris, Saturday, May 24, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)

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Defending champion Serena Williams, of the U.S, attends the Men's singles draw for the French Open Tennis tournament, at the Roland Garros stadium in Paris, Friday, May 23, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)

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Serena Williams of the U.S., returns the ball while her coach Patrick Mouratoglou, right, looks on during a training session for the French Open tennis tournament, at the Roland Garros stadium in Paris, Saturday, May 24, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)

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Kei Nishikori, of Japan, returns the ball during a training session for the French Open tennis tournament, at the Roland Garros stadium in Paris, Friday, May 23, 2014. The French Open tennis tournament starts Sunday. (AP Photo/Michel Euler)