Local fans were looking for a big day in the quarterfinals with three Germans in the four matches. But Kohlschreiber was the only local favorite to advance as Haas and unseeded Michael Berrer both were beaten.
Fifth-seeded Fabio Fognini eliminated Haas 6-2, 6-4 without dropping serve. Haas had five break chances but Fognini fended them all off. Fognini won more than 70 percent of the points on serve.
Berrer was forced to retire from his match because of a left elbow injury. Roberto Bautista Agut was up 6-2, 1-0 when the match was stopped.
Kohlschreiber got by Gael Monfils 6-4, 6-4 with two breaks in each set. His second-set breaks came early and allowed him to win even after Monfils broke and then got back to 5-4.
Victor Hanescu earned his first ATP semifinal spot in 12 years with a 7-5, 6-2 upset of fourth-seeded Benoit Paire, against whom he is 4-0. Hanescu saved the only break point he faced Friday.
Kohlschreiber will play Hanescu in Saturday's semifinals. They each won one of their two previous meetings, with Kohlschreiber taking a three-set decision at the French Open earlier this year. Fognini and Bautista Agut have also played twice before, splitting highly competitive matches.