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 .
Serena Williams out of the Australian Open after fourth round defeat . Serbian Ana Ivanovic beats American world No.1 4-6 6-3 6-3 . Williams blames her loss on a `` tremendous amount of errors '' In the men 's draw , Novak Djokovic sets up quarterfinal against old foe Stanislas Wawrinka .