MELBOURNE, AUSTRALIA - JANUARY 14: Novak Djokovic with coach Andre Agassi during a practice session ahead of the 2018 Australian Open at Melbourne Park on January 14, 2018 in Melbourne, Australia. (Photo by James D. Morgan/Getty Images)
MELBOURNE, AUSTRALIA - JANUARY 14: Novak Djokovic with coach Andre Agassi during a practice session ahead of the 2018 Australian Open at Melbourne Park on January 14, 2018 in Melbourne, Australia. (Photo by James D. Morgan/Getty Images)