MELBOURNE, AUSTRALIA - JANUARY 12: Roger Federer of Switzerland serves during a practice session ahead of the 2017 Australian Open at Melbourne Park on January 12, 2017 in Melbourne, Australia. (Photo by Scott Barbour/Getty Images)
MELBOURNE, AUSTRALIA - JANUARY 12: Roger Federer of Switzerland serves during a practice session ahead of the 2017 Australian Open at Melbourne Park on January 12, 2017 in Melbourne, Australia. (Photo by Scott Barbour/Getty Images)