NUEVA YORK -SEPTIEMBRE 1, 2015: Diecisiete veces campeón del Grand Slam Roger Federer de Suiza en acción durante el partido del Abierto de Estados Unidos 2015 en el National Tennis Center de Nueva York - Foto e imagen de stock

NEW YORK - AUGUST 31, 2017: Grand Slam champion Roger Federer of Switzerland in action during his US Open 2017 round 2 match at Billie Jean King National Tennis Center

NEW YORK -SEPTEMBER 1, 2015: Seventeen times Grand Slam champion Roger Federer of Switzerland in action during first round US Open 2015 match at National Tennis Center in NY

NEW YORK -SEPTEMBER 1, 2015: Seventeen times Grand Slam champion Roger Federer of Switzerland in action during first round US Open 2015 match at National Tennis Center in NY

NEW YORK - AUGUST 31, 2017: Grand Slam champion Roger Federer of Switzerland in action during his US Open 2017 round 2 match at Billie Jean King National Tennis Center

FLUSHING, NY -SEPTEMBER 2: Seventeen times Grand Slam champion Roger Federer during his fourth round match at US Open 2013 against Tommy Robredo at Billie Jean King National Tennis Center on September 2, 2013 in Flushing, NY

NEW YORK - AUGUST 24: Seventeen times Grand Slam champion Roger Federer practices for US Open 2014 at Billie Jean King National Tennis Center on August 24 , 2014 in New York

FLUSHING, NY - AUGUST 27 Seventeen times Grand Slam champion Roger Federer during his first round match at US Open 2013 against Grega Zemlja at Billie Jean King National Tennis Center on August 27, 2013 in Flushing, NY

FLUSHING, NY - AUGUST 27: Seventeen times Grand Slam champion Roger Federer during his first round match at US Open 2013 against Grega Zemlja at Billie Jean King National Tennis Center on August 27, 2013 in Flushing, NY

NEW YORK -SEPTEMBER 2, 2014: US Open 2014 champion Marin Cilic from Croatia during US Open 2014 round 4 match against Gilles Simon at Billie Jean King National Tennis Center in New York

NEW YORK -SEPTEMBER 1, 2015: Seventeen times Grand Slam champion Roger Federer of Switzerland in action during first round US Open 2015 match at National Tennis Center in NY

FLUSHING, NY - SEPTEMBER 7: Professional tennis player Richard Gasquet during his semifinal match at US Open 2013 against twelve times Grand Slam champion Rafael Nadal at Arthur Ashe Stadium on September 7, 2013 in Flushing, NY

NEW YORK -SEPTEMBER 1, 2015: Seventeen times Grand Slam champion Roger Federer of Switzerland in action during first round US Open 2015 match at National Tennis Center in NY

FLUSHING, NY -SEPTEMBER 2: Seventeen times Grand Slam champion Roger Federer during his fourth round match at US Open 2013 against Tommy Robredo at Billie Jean King National Tennis Center on September 2, 2013 in Flushing, NY

FLUSHING, NY - SEPTEMBER 9 US Open 2013 finalist Novak Djokovic during his final match against champion Rafael Nadal at Billie Jean King National Tennis Center on September 9, 2013 in Flushing, NY

NEW YORK - SEPTEMBER 1, 2018: Professional tennis player Alexander Zverev of Germany in action during his 2018 US Open round of 32 match at Billie Jean King National Tennis Center

NEW YORK - SEPTEMBER 4, 2017: Grand Slam champion Roger Federer of Switzerland in action during his US Open 2017 round 4 match at Billie Jean King National Tennis Center

FLUSHING, NY - AUGUST 26 Twelve times Grand Slam champion Rafael Nadal during his first round match at US Open 2013 against Ryan Harrison at Arthur Ashe Stadium on August 26, 2013 in Flushing, NY

FLUSHING, NY - AUGUST 19: Seventeen times Grand Slam champion Roger Federer practices for US Open 2013 at Arthur Ashe Stadium at Billie Jean King National Tennis Center on August 19, 2013 in Flushing, NY

NEW YORK - AUGUST 22, 2018: 20-time Grand Slam champion Roger Federer of Switzerland practices for the 2018 US Open at Billie Jean King National Tennis Center

NEW YORK - AUGUST 27 Seventeen times Grand Slam champion Roger Federer during his first round match at US Open 2013 against Grega Zemlja at Billie Jean King National Tennis Center on August 27, 2013 in New York

NEW YORK- AUGUST 31: Grand Slam champion Roger Federer during third round match at US Open 2014 against Marcel Granollers at Billie Jean King National Tennis Center on August 31, 2014 in New York

NEW YORK - SEPTEMBER 2, 2017: Professional tennis player Dominic Thiem of Austria in action during his US Open 2017 round 3 match at Billie Jean King National Tennis Center

NEW YORK- AUGUST 31: Grand Slam champion Roger Federer during third round match at US Open 2014 against Marcel Granollers at Billie Jean King National Tennis Center on August 31, 2014 in New York

NEW YORK - AUGUST 22, 2018: 20-time Grand Slam champion Roger Federer of Switzerland practices for the 2018 US Open at Billie Jean King National Tennis Center

NEW YORK - AUGUST 31, 2017: Grand Slam champion Roger Federer of Switzerland in action during his US Open 2017 round 2 match at Billie Jean King National Tennis Center