( CNN ) -- Top seed Rafael Nadal and second seed Roger Federer are both through to the quarterfinals of the Qatar Open in Doha after comfortable straight sets victories on Wednesday . French Open champion Nadal took 90 minutes to see off fellow-left-hander Denis Gremelmayr of Germany 6-2 6-2 while Federer 's 6-2 6-3 success over Slovenian Grega Zemlja was achieved in exactly and hour . Nadal told reporters he was happy with the way he played , saying : `` The worst thing I did last year was my return and I was happy with the way my return worked today . `` I also want to have enough shots not to be predictable . I want to attack the ball faster and hit with more power and spin , '' he added . Both Nadal and Federer had to contend with a troublesome wind and Federer said : `` I used to be very emotional when I was younger , after growing up in Switzerland where we did n't have wind that much , and where we also played indoors a lot . `` It was difficult learning how to play in the wind -- but I have had a lot of practice playing in windy places and it does n't bother me any more . '' Federer next faces eighth-seeded Italian Andreas Seppi , while Nadal will take on Russian Mikhail Youzhny . Also through to the quarterfinals are third seed Jo-Wilfried Tsonga and fifth seed Viktor Troicki . Top seed Andy Murray is through to the last eight of the Brisbane International event but he had to fight back from the brink of defeat for the second successive match , eventually beating Luxembourg 's Gilles Muller 4-6 7-6 6-0 . The Briton next faces Cypriot Marcos Baghdatis , who dumped out fifth seed Kei Nishikori of Japan 6-3 6-4 .
Rafael Nadal and Roger Federer through to the quarterfinals of Qatar Open . Top-seeded Spaniard Nadal defeats Denis Gremelmayr of Germany 6-2 6-2 . Second seed Federer eases past Slovenian Grega Zemlja 6-2 6-3 in Doha . There are also wins for Jo-Wilfried Tsonga and Viktor Troicki on Wednesday .