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Rafael Nadal of Spain keeps his eyes on the ball as he plays Rogerio Dutra Silva of Brazil at the U.S. Open tennis championships in New York

Rafael Nadal of Spain keeps his eyes on the ball as he plays Rogerio Dutra Silva of Brazil at the U.S. Open tennis championships in New York, August 29, 2013. REUTERS/Shannon Stapleton (UNITED STATES - Tags: SPORT TENNIS)