Rafa Nadal's preparations for Wimbledon were cut short when he was knocked out of the Halle Open by defending champion Philipp Kohlschreiber, while Roger Federer was taken to three sets by Milos Raonic in their quarter-final.
Kohlschreiber triumphed 6-3 6-4, four days after Nadal won a record seventh French Open title at Roland Garros.
It was the first time the German had beaten Nadal after eight previous defeats, although this was their first meeting on grass.
Kohlschreiber will face the winner of Czech third seed Tomas Berdych's match against wildcard Tommy Haas in the semi-finals.
Federer was taken to the wire by big-serving Canadian Raonic, losing the first set before coming through 6-7 6-4 7-6.
Raonic served 25 aces but that was not enough to halt the Swiss's march into the last four where he will face Mikhail Youzhny, who beat Radek Stepanek 6-4 4-6 6-4.