Novak Djokovic of Serbia (L) and Serena Williams of the US play during a Kids Day exhibition match ahead of the upcoming Australian Open tennis tournament in Melbourne on January 12, 2013. The first Grand Slam tennis tournament of the year is set to run from January 14 to 27. AFP PHOTO / MANAN VATSYAYANA IMAGE STRICTLY RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE (Photo credit should read MANAN VATSYAYANA/AFP via Getty Images)
