Novak Djokovic, at the Australian Open tennis championships, in Melbourne, Australia. 喬科維奇

Novak Djokovic of Serbia reacts during his third round match against Andreas Seppi of Italy at the Australian Open tennis championships in Melbourne, Australia, Friday, Jan. 22, 2016.(AP Photo/Vincent Thian) - See more at: http://www.whio.com/ap/ap/top-news/nishikori-goffin-reach-4th-round-at-australian-ope/np9R3/#sthash.2unIAWS5.dpuf