French Open champion Rafael Nadal started his grass-court season in style with an impressive 7-5 6-1 win over Lukas Lacko at the Gerry Weber Open.
Nadal needed just 75 minutes to secure a quarter-final clash with defending champion Philipp Kohlschreiber.
Kohlschreiber, who has never beaten Nadal, hit 11 aces in his 6-7 (5-7) 6-1 6-3 win over Poland's Lukasz Kubot.
Five-time champion Roger Federer also reached the last eight with a 6-4 7-5 victory over Florian Mayer.
The Swiss broke once in each set to progress in one hour and 14 minutes, setting up a clash with Milos Raonic, who beat Ze Zhang 6-1 6-1.
There was an impressive performance too from veteran German Tommy Haas who defeated sixth seed Marcel Granollers 6-3 6-4.