In the remaining 4th round match Djokovic beat Wawrinka in straight sets.
So the quarter finals are:
Federer (1) v Berdych (6)
Murray (3) v Cilic (12)
Tipsarevic (8) v Ferrer (4)
Del Potro (7) v Djokovic (2)
Berdych beat Federer 7-6, 6-4, 3-6, 6-3 to get to the semi-finals. He plays Murray who had looked to be going out having lost the first set and was 1-5 down in the second. Murray came back to win 3-6, 7-6, 6-2, 6-0.
In the women's singles quarter finals, there were wins for each of the higher ranked players with wins for Victoria Azarenka, Maria Sharapova, Serena Williams, and Sara Errani.
So the semi finals will be Azarenka v Sharapova and Williams v Errani. The first of those matches could be quite some match. The second match, Serena Williams must be strong favourite to win, the way she's been playing recently.