Ryan Harrison of the US serves to Serbia's Novak Djokovic during their second round match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 16, 2013. (AP Photo/Rob Griffith)

Associated Press
Ryan Harrison of the US serves to Serbia's Novak Djokovic during their second round match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 16, 2013. (AP Photo/Rob Griffith)
Ryan Harrison of the US serves to Serbia's Novak Djokovic during their second round match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Jan. 16, 2013. (AP Photo/Rob Griffith)
View Comments (0)