Rafael Nadal has lost in straight sets in the Gerry Weber Open quarter-finals to defending champion Philipp Kohlschreiber of Germany.
Top seed Nadal was on a 13-match winning run that including a record seventh French Open triumph, but went down 6-3 6-4 to Kohlschreiber in Halle.
Kohlschreiber will play Tommy Haas in the last eight after the German beat third seed Tomas Berdych 6-4 3-6 7-5.
Second seed Roger Federer overcame Milos Raonic 6-7 (4-7) 6-4 7-6 (7-3).
The five-time champion will next face Russia's Mikhail Youzhny, who beat Radek Stepanek 6-4 4-6 6-4.
Federer's path to the title looks less problematic following Nadal's defeat by eighth seed Kohlschreiber.
"I said it was going to be tough," said Nadal. "He plays well on this court. You just have to congratulate him.
"He played very aggressively, served well, returned well. He played better than me. I was suffering when he was serving. I didn't have that energy to change the situation."
Nadal confirmed he would now be heading home to Mallorca to rest ahead of Wimbledon, which starts on 25 June.
"I can't practice on grass there but it's better not to practice for a few days. It's time to rest with my family, friends, to relax," he added.
"I've played almost every match possible since Indian Wells. When I'm ready to come back, I'll go to Wimbledon."
Nadal was in difficulty from his first service game and Kohlschreiber, the eighth seed, wrapped up the first set in just over 30 minutes.
After saving two breaks in game one of the second set, Nadal then wasted three chances to break in game four.
Kohlschreiber kept calm to seal a fine victory and reach the last four.