Marin Cilic and fellow Croatian Ivo Karlovic set up a big-serving semi-final clash at the Den Bosch Open after impressive victories at the Dutch grasscourt event.
Rising German Alexander Zverev also advanced to the last four, as did Luxembourg's Gilles Muller meaning the top four seeds have also survived to the semis.
World No.7 Cilic recorded his 50th grasscourt match win, beating Vasek Pospisil 6-3 7-5.
"I feel better and better, obviously after each day I'm getting used to the grass," Cilic, who recovered a 5-2 second-set deficit, said. "I served well in critical situations."
The 38-year-old Karlovic reached his first semi-final of the year after the third seed beat qualifier Daniil Medvedev 6-4 6-4 in less than an hour on court.
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"I was playing unbelievable, with some really good volleys. Overall I am happy with the performance," he said.
Zverev, 20, was also occupied for less than an hour as he beat 35-year-old Frenchman Julien Benneteau 6-0 6-4 while Muller beat Britain's Aljaz Bedene 6-3 3-6 6-4.
