PHOTOS: Big upsets on Day 4 at Australian Open

From potential dark horses to former champions, here are the players who were knocked out of  the Australian Open on Thursday Wawrinka sent out by Sandgren IMAGE: Switzerland's Stan Wawrinka......

Aus Open PHOTOS: Federer, Djokovic, Zverev battle through, Sharapova to face Kerber; Muguruza, Wawrinka out

Images from matches played on Day 4 of the Australian Open at Melbourne Park on Thursday IMAGE: Roger Federer of Switzerland hits a shot against Jan-Lennard Struff of Germany. Photograph: Thomas......