Wozniacki broke open a tough match against Tsvetana Pironkova by winning seven straight games and racking up a 6-4, 6-1 win Saturday.
Petrova had her hands full with Roberta Vinci of Italy. Vinci prevailed in a 70-minute first set, but Petrova chalked up two breaks in the second set and another in the third set to notch the win.
Petrova will be contending for her third title of the year Sunday. She last won in September's Pan Pacific Open.
Wozniacki is 2-1 in finals this year, with wins this fall at the Korea Open and Kremlin Cup.