Novak Djokovic of Serbia, Daria Gavrilova of Australia, Milos Raonic of Canada and Roger Federer of Switzerland (from L to R) pose for a photo during an exhibition match at Melbourne Park in Melbourne, Australia, Jan. 14, 2017. An exhibition match on Kids Tennis Day was held ahead of Australian Open 2017 at Melbourne Park on Saturday. Australian Open 2017 will take place at Melbourne Park from Jan. 16 to Jan. 29. (Xinhua/Bai Xue)