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NEW YORK, NY - AUGUST 28: Roger Federer of Switzerland during day 2 of the 2018 US Open at Arthur Ashe Stadium of USTA Billie Jean King National Tennis Center on August 28, 2018 in Flushing Meadows, Queens, New York City. (Photo by Jean Catuffe/Getty Images)

NEW YORK, NY - AUGUST 28: Roger Federer of Switzerland during day 2 of the 2018 US Open at Arthur Ashe Stadium of USTA Billie Jean King National Tennis Center on August 28, 2018 in Flushing Meadows, Queens, New York City. (Photo by Jean Catuffe/Getty Images)