The 2010 champions reached the last eight on Saturday when Viktor Troicki and Nenad Zimonjic defeated Belgian pair SteveDarcis and Ruben Bemelmans in four sets 6-4 6-4 5-7 6-4.
Top seed Federer was taken all the way by Latvian Ernests Gulbis before going through 6-2 4-6 6-4, while Nadal had a simpler task to overcome Belgian SteveDarcis -- who retired while trailing 6-1 2-0.