Canada's Milos Raonic was knocked out of the Gerry Weber Open after a 6-4, 6-4 loss to German qualifier Peter Gojowczyk on Wednesday.
Raonic, the No. 3 seed from Thornhill, Ont., failed to break Gojowczyk in two tries and lost in a match that took one hour 12 minutes to complete.
Gojowczyk moves on to the quarter-finals where he will face Colombia's Alejandro Falla, who beat Dutchman Robin Haase 7-6 (1), 6-4.
Earlier, former champion Philipp Kohlschreiber advanced to the quarter-finals with a 6-2, 6-4 win over French qualifier Pierre-Hugues Herbert.
Kohlschreiber, who won the grass-court tournament in 2011, will next play Rafael Nadal or German compatriot Dustin Brown.
Fourth-seeded Kei Nishikori booked his quarter-final place by beating Gael Monfils 6-1, 3-6, 6-3.