The top seed and defending champion Novak Djokovic remains on track for a fifth grand slam title after surviving a tenacious Lleyton Hewitt to move into the quarter-finals.
Five-times champion Serena Williams lost for the first time in four years dumped out by world number 56 Ekaterina Makarova and Djokovic, who had not dropped a set in three quick-fire wins at the year's first grand slam, battled for almost three hours with the 30-year-old Hewitt before completing a four sets win.
The Serbian world number one says he expected nothing else from the obdurate Australian.
Djokovic will face Spanish world number five and Heineken Open champion David Ferrer in the quarter-finals.
The feature matches this afternoon pit the womens top seed Caroline Wozniacki against defending champion Kim Clijsters and four times champion Roger Federer against Juan Martin del Potro.