Halle - Defending champion Tommy Haas reached the quarter-finals of the Gerry Weber Open on Thursday beating Ernests Gulbis, 7-6 (7/5), 6-4, after the Latvian had saved 16 of 17 break points.
World number 11 Haas will face France's Gael Monfils for a place in the semi-finals.
Haas is one of four German players to make the last-eight after Philipp Kohlschreiber, Florian Mayer and Mischa Zverev.
He is making his 13th appearance at the pre-Wimbledon warm-up and took the title for the first time in 2012, beating Roger Federer in the final.
Results from the fourth day of the ATP Halle Open (x denotes seeding):
Tommy Haas (GER x3) bt Ernests Gulbis (LAT) 7-6 (7/5), 6-4
Philipp Kohlschreiber (GER x6) bt Tobias Kamke (GER) 6-4, 6-3
Florian Mayer (GER x8) bt Leonardo Mayer (ARG) 6-2, 6-3
Richard Gasquet (FRA x2) bt Jurgen Melzer (AUT) 6-3, 6-1