World number one Roger Federer was made to work hard before he edged out France's Richard Gasquet 7-6, 6-7, 6-4 to reach the quarter-finals of the Halle International on Thursday.
The three-times champion, unbeaten on grass since losing in the first round at Wimbledon in 2002, chalked up his 38th consecutive win on the turf.
If he captures the title here, the Wimbledon holder will equal Bjorn's Borg's professional era record of 41 consecutive wins on the surface.
"It is hard for me to play consistently from the baseline and that is where he had the edge today," Federer, who will next meet Belgian seventh seed Olivier Rochus, told reporters.
"I have now found my tournament rhythm and am settled into the grasscourt season."
Marat Safin missed out on setting up a repeat of last year's final against Federer after he was beaten 4-6, 6-4, 6-1 by Rochus.
Fifth seed Tomas Berdych was also pushed before he won the all-Czech battle with a 6-3 6-7 7-5 victory over Jiri Novak.