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CINCINNATI, OH - AUGUST 18: Roger Federer of Switzerland returns a shot to Roberto Bautista Agut of Spain during Day 4 of the Western & Southern Open at the Linder Family Tennis Center on August 18, 2015 in Cincinnati, Ohio. (Photo by Rob Carr/Getty Images)

CINCINNATI, OH - AUGUST 18:  Roger Federer of Switzerland returns a shot to Roberto Bautista Agut of Spain during Day 4 of the Western & Southern Open at the Linder Family Tennis Center on August 18, 2015 in Cincinnati, Ohio.  (Photo by Rob Carr/Getty Images)