Second seed Tommy Sugiarto was knocked out of the Bitburger Open by Tzu Wei Wang of Chinese Taipei on Thursday.
The Indonesian shuttler did well to win the second game after being outplayed in the first, but Wang again pulled away in the decider to secure a 21-10 20-22 21-10 victory.
Top seed Chou Tien Chen had no such problems against Dionysius Hayom Rumbaka, advancing to the quarter-finals with a 21-17 21-16 victory.
Malaysia's Wei Feng Chong was beaten by third seed Marc Zwiebler of Germany, losing 17-21 21-13 21-17, while fourth seed Hans-Kristian Vittinghus dispatched Joachim Persson 21-14 21-16.
Top seeded doubles pair Mads Conrad-Petersen and Mads Pieler Kolding advanced with a 21-18 21-16 victory over Danish countrymen Mathias Christiansen and David Daugaard, while top seeds Cris and Gabrielle Adcock of England also reached the last eight in the mixed doubles, beating Japan's Keigo Sonoda and Naoko Fukuman.