Serbia's Novak Djokovic makes a forehand return to Ryan Harrison of the US during their second round match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 16, 2013. (AP Photo/Rob Griffith)
Serbia's Novak Djokovic makes a forehand return to Ryan Harrison of the US during their second round match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 16, 2013. (AP Photo/Rob Griffith)
Ryan Harrison returns a shot to Mischa Zverev during a match at the Legg Mason Classic on Tuesday. The 19-year-old American won, 6-3, 1-6, 6-1. (AP Photo/Nick Wass)
