MELBOURNE, AUSTRALIA - JANUARY 17: Juan Martin del Potro of Argentina hits a forehand during a practice session ahead of the 2015 Australian Open at Melbourne Park on January 17, 2015 in Melbourne, Australia. (Photo by Michael Dodge/Getty Images)
MELBOURNE, AUSTRALIA - JANUARY 17: Juan Martin del Potro of Argentina hits a forehand during a practice session ahead of the 2015 Australian Open at Melbourne Park on January 17, 2015 in Melbourne, Australia. (Photo by Michael Dodge/Getty Images)