World number one Roger Federer breezed through to the Halle Open semi-finals with a 6-3, 6-4 win over Germany's Philipp Kohlschreiber on Friday.
He was joined in the last four by Russian second seed Marat Safin, who beat Belgian Olivier Rochus 6-4, 7-6 and German Tommy Haas, who defeated Spain's Juan Carlos Ferrero 6-2, 7-5.
Guillermo Canas of Argentina also went through after ousting local favourite Rainer Schuettler 6-4, 6-4.
Top seed Federer, aiming for his third consecutive victory at the pre-Wimbledon grasscourt event, was much too strong for the unseeded young German in a match lasting just over an hour.
"I played tough and consistent and when I needed to serve well I did that too," Federer told a news conference.
"I thought today was a solid performance and exactly what I needed against a player like him," he added.
The 23-year-old Swiss is also going for a third successive Wimbledon title at the All England Club in London starting on June 20.
"I really have the feeling that every match I'm playing on the grass now I'm getting to focus just that extra bit every time I step out again so I'm really happy," Federer said.
Kohlschreiber failed to convert several break points and said Federer, who came within two points of defeat against Robin Soderling in the first round, was not invincible on grass.
"You can see he is beatable," the 21-year-old said. "I think at some point the time will come when he loses."
Federer will play Haas in the semis after the seventh seed overpowered former world number one Ferrero.
Haas, 27, had never beaten the Spaniard in three previous matches, all on clay. But he played aggressively in front of his home fans to keep the pressure on the former French Open champion and said he was looking forward to playing Federer.
"It's definitely going to be great," Haas said.
"Our last match was before my shoulder operation and since then Roger has conquered the tennis world."
Safin came through his match despite a troublesome knee injury which is clouding his Wimbledon preparations.
"I think it will be okay," Safin said. "I hope the doctor will help me out because it's quite sore. We'll see."