Νέα Υόρκη-31 Αυγούστου 2015: επαγγελματίας τενίστρια Κέι Νισκόρι της Ιαπωνίας σε δράση κατά τη διάρκεια του πρώτου γύρου αγώνων στο The Open 2015 στο εθνικό κέντρο τένις της Μπίλι Jean King στη Νέα Υόρκη - Φωτογραφίες & Εικόνες Αρχείου

NEW YORK -SEPTEMBER 5, 2016: Professional tennis player Kei Nishikori of Japan in action during his round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK -SEPTEMBER 5, 2016: Professional tennis player Kei Nishikori of Japan in action during his round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK -SEPTEMBER 5, 2016: Professional tennis player Kei Nishikori of Japan in action during his round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK -SEPTEMBER 5, 2016: Professional tennis player Kei Nishikori of Japan in action during his round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - AUGUST 25, 2015: Grand Slam Champion Andy Murray practices for US Open 2015 at Billie Jean King National Tennis Center in New York

FLUSHING, NY - AUGUST 26 Professional tennis player Andreas Haider-Maurer from Austria during his first round match against Ernests Gulbis from Latvia at US Open 2013 on August 26, 2013 in Flushing, NY

NEW YORK - AUGUST 30, 2016: Professional tennis player Kei Nishikori of Japan in action during his first round match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 4, 2016: Professional tennis player Jack Sock of United States in action during his round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - AUGUST 30, 2016: Professional tennis player Kei Nishikori of Japan in action during his first round match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - AUGUST 30, 2016: Professional tennis player Kei Nishikori of Japan in action during his first round match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - AUGUST 31, 2015: Professional tennis player Kei Nishikori of Japan in action during first round match at US Open 2015 at Billie Jean King National Tennis Center in New York

NEW YORK -SEPTEMBER 5, 2016: Professional tennis player Kei Nishikori of Japan in action during his round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK -SEPTEMBER 5, 2016: Professional tennis player Kei Nishikori of Japan in action during his round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - AUGUST 22, 2018: American retired professional tennis player James Blake in action during 2018 US Open exhibition match at newly open Louis Armstrong Stadium at National Tennis Center

NEW YORK - SEPTEMBER 5, 2016: Professional tennis player Illya Marchenko of Ukraine in action during his fourth round match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - AUGUST 31, 2015: Professional tennis player Kei Nishikori of Japan in action during first round match at US Open 2015 at Billie Jean King National Tennis Center in New York

FLUSHING, NY - AUGUST 24: Professional tennis player Ricardas Berankis practices for US Open 2013 at Billie Jean King National Tennis Center on August 24, 2013 in Flushing, NY

FLUSHING, NY - AUGUST 20: Two times Grand Slam champion Lleyton Hewitt practices for US Open 2013 at Louis Armstrong Stadium at Billie Jean King National Tennis Center on August 20, 2013 in Flushing, NY