“This is not really how I want to win my games, it is a bit uncomfortable,” said the five-times Halle champion. “Now I need to switch from today’s match to tomorrow’s difficult encounter.”
Haas had a much harder time against Frenchman Gael Monfils and battled into the last four with a 6-7(4/7), 6-3, 6-3 win.
The former world No. 2 failed to earn a single break point in the first set, but twice got the better of Monfils in the next two.
A sizzling trademark one-handed backhand down the line gave the German a 4-2 lead in the third and the chance to serve out the match two games later.
Frenchman Richard Gasquet beat Germany’s Florian Mayer 6-3, 7-6 (7/4) to set up a semi-final against Mikhail Youzhny of Russia.