Top-seeded Marin Cilic of Croatia needed three sets to beat sixth-seeded Nicolas Almagro of Spain 6-4, 6-7 (2), 6-2 and stay on course for his third title of the year.
Two-time runner-up Mikhail Youzhny of Russia, who lost last year's final to Berdych, eased into the semifinals by beating Jiri Hajek of the Czech Republic 6-1, 6-3.
Fifth-seeded Marcos Baghdatis of Cyprus reached his second semifinal of the year by beating fourth-seeded Philip Kohlschreiber of Germany 6-3, 6-4. Kohlschreiber won the tournament in 2007.
Baghdatis saved three break points before serving out the match. He will next play Cilic.
The third-seeded Berdych had won both previous matches against Petzschner, but the German broke Berdych's serve for a decisive 5-4 lead in the third set, after Berdych had saved three break points.
Petzschner will next play the second-seeded Youzhny.