Wozniacki, who held the year-end No. 1 ranking in 2010 and 2011 but is yet to win a major title, had high-profile support from boyfriend and golf No. 1 Rory McIlroy in the crowd but struggled with her serve as she surrendered the second set and then had difficulty in the third countering the powerful groundstrokes from the left-handed Pervak.
The 103-ranked Pervak was two points from victory, serving for the match at 5-3 and 30-15, but made a series of unforced errors to let the 10th-ranked Wozniacki back into the contest. Pervak dominated the tiebreaker, winning the first five points.