Petrova, the defending champion, has been suffering from a viral infection and she said she felt too weak to play after dropping the first set in a tiebreak.
That put Czink in the semifinals against Aleksandra Wozniak, who is two victories away from the first tournament title of her career.
Wozniak coasted past Alla Kudrysvtseva in their quarterfinal matchup 6-1, 6-2.
The other semifinal will send Lucie Safarova against Julia Goerges.
Safarova was a 6-3, 6-4 winner over Bethanie Mattek-Sands, who lost to Petrova in the finals of this event last year. Goerges defeated Lilia Osterloh 6-2, 6-4.
Copyright 2009 by United Press International.