Serena pulled out of the Australian Open after fourth round defeat . `` Maybe I was n't the best physically , but that had nothing to do with it . Serbian Ana ##ity beats American world No.1 4 - 6 6 - 3 6 - 3 . Williams blamed her loss on a ` ` tremendous series of errors '' In the men 's draw , Novak Djokovic sets up quarterfinal against old foe Stanislas David .
Serena pulled out of the Australian Open after fourth round defeat . Serbian Ana ##ity beats American world No.1 4 - 6 6 - 3 6 - 3 . Williams blamed her loss on a ` ` tremendous series of errors '' In the men 's draw , Novak Djokovic sets up quarterfinal against old foe Stanislas David .