Roger Federer beat Matthew Ebden to win his 19th successive match on grass and reach the Halle Open semi-finals.
The Swiss, who is aiming for a 10th title in Germany, beat Australian world number 60 Ebden 7-6 (7-2) 7-5.
Victory in Halle will ensure 36-year-old Federer retains his world number one ranking.
He will face qualifier Denis Kudla in the next round, following the American's 6-2 7-5 win over Yuichi Sugita of Japan.
Federer hit 43 winners to Ebden's 32, but the 20-time Grand Slam champion had to come back from a break down to ensure victory.
After dominating the first set tie-break, Federer trailed his 30-year-old opponent 4-3 in the second set after a poor return game.
However, he rallied to win the final four games for victory in 89 minutes.