Top seed Roger Federer qualified for his 15th quarter final at the Gerry Weber Open with a straight-sets victory over Mischa Zverev.
The 7-6 (7/4) 6-4 win will earn the Swiss a top-four seeding at Wimbledon and he has now won four out of four against the German.
Zverev saved three set points on his own serve at 4-5 to take the opening set into a tie-break but two passing shot winners from Federer at 5/4 saw him close it out.
Federer's forehand winner at 4-4 secured the only break of the match and he served out to wrap up victory in one hour and 30 minutes.
Federer will face Florian Mayer in the quarter-finals following his 6-7 (6/8) 6-4 6-3 victory over the sixth-seeded Lucas Pouille.
Kei Nishikori suffered another injury scare when he was forced to retire early in his clash against Karen Khachanov with a hip problem.
It is the third year in a row that the world number nine has pulled out during a match at the pre-Wimbledon event.
Khachanov was leading 3-2 when Nishikori called it a day and will take on fellow young Russian Andrey Rublev in the quarter-finals.
Rublev, 19, is through to the last eight at an ATP event for the first time after a 6-0 3-6 6-3 victory over Mikhail Youzhny.
