SYDNEY, AUSTRALIA - JANUARY 11: Rafael Nadal of Spain serves during the FAST4Tennis exhibition match between Rafael Nadal and Lleyton Hewitt at Allphones Arena on January 11, 2016 in Sydney, Australia. (Photo by Zak Kaczmarek/Getty Images)
SYDNEY, AUSTRALIA - JANUARY 11: Rafael Nadal of Spain serves during the FAST4Tennis exhibition match between Rafael Nadal and Lleyton Hewitt at Allphones Arena on January 11, 2016 in Sydney, Australia. (Photo by Zak Kaczmarek/Getty Images)