Serena Williams of the United States makes a forehand return to Vesna Dolonc of Serbia during their second round match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 15, 2014.(AP Photo/Aaron Favila)
Novak Djokovic of Serbia celebrates after defeating Lukas Lacko of Slovakia in their first round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 13, 2014..(AP Photo/Aaron Favila)