PERTH, AUSTRALIA - DECEMBER 23: Roger Federer of Switzerland plays a forehand during a practice session at the Perth Arena on December 29, 2016 in Perth, Australia. (Photo by Paul Kane/Getty Images)
PERTH, AUSTRALIA - DECEMBER 23: Roger Federer of Switzerland plays a forehand during a practice session at the Perth Arena on December 29, 2016 in Perth, Australia. (Photo by Paul Kane/Getty Images)