Sydney, Australia (SportsNetwork.com) - Caroline Wozniacki retired from Monday's first-round match at the Sydney International with a wrist injury.

The fourth-seeded Dane dropped the opening set to Czech Barbora Zahlavova Strycova 6-4, then called it quits with the second set even at 1-1. Wozniacki was coming off a loss to Venus Williams in Saturday's ASB Classic final.

Sixth-seeded Russian Ekaterina Makarova posted a 7-6 (7-1), 6-2 win over Ukraine's Elina Svitolina and seventh-seeded Slovakian Dominika Cibulkova, the 2013 Sydney finalist, defeated French qualifier Kristina Mladenovic 6-2, 6-2.

Another qualifier, Tsvetana Pironkova of Bulgaria, knocked out eighth-seeded Italian Flavia Pennetta 6-3, 7-6 (7-4).

Aussie Samantha Stosur, the 2005 runner-up at this hardcourt event, outlasted Czech Lucie Safarova 7-6 (7-3), 5-7, 6-3 in a match that lasted over three hours.