Switzerland

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Venus Williams of the US serves the ball during the first round match of the French Open tennis tournament against Switzerland's Belinda Bencic at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/David Vincent)

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Venus Williams of the US serves the ball during the first round match of the French Open tennis tournament against Switzerland's Belinda Bencic at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/David Vincent)

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Venus Williams of the US serves the ball during the first round match of the French Open tennis tournament against Switzerland's Belinda Bencic at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/David Vincent)

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Switzerland's Roger Federer serves the ball during the first round match of the French Open tennis tournament against Slovakia's Lukas Lacko at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/Darko Vojinovic)

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Switzerland's Roger Federer returns the ball during the first round match of the French Open tennis tournament against Slovakia's Lukas Lacko at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/Darko Vojinovic)

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Slovakia's Lukas Lacko returns the ball during the first round match of the French Open tennis tournament against Switzerland's Roger Federer at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/Darko Vojinovic)

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Switzerland's Roger Federer returns the ball during the first round match of the French Open tennis tournament against Slovakia's Lukas Lacko at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/Darko Vojinovic)

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Switzerland's Roger Federer prepares to serve the ball during the first round match of the French Open tennis tournament against Slovakia's Lukas Lacko at the Roland Garros stadium, in Paris, France, Sunday, May 25, 2014. (AP Photo/Darko Vojinovic)