Sydney, Australia (SportsNetwork.com) - Third-seeded former champion Agnieszka Radwanska moved on, while former world No. 1 Caroline Wozniacki retired from her first-round match Monday at the Sydney International tennis event because of a wrist injury.

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

Meanwhile, Radwanska rolled past France's Alize Cornet 6-3, 6-2 and fifth- seeded German and last year's Sydney runner-up, Angelique Kerber, overcame Ukrainian qualifier Lesia Tsurenko 1-6, 6-4, 6-3 on Day 2.

Sixth-seeded Russian Ekaterina Makarova posted a 7-6 (7-1), 6-2 win over Ukraine's Elina Svitolina and seventh-seeded Slovakian, 2103 Sydney runner-up and last year's Aussie Open runner-up Dominika Cibulkova defeated French qualifier Kristina Mladenovic 6-2, 6-2.

Another qualifier, last year's Sydney champion 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 exceeded three hours.

Also on Monday, Aussie wild card Jarmila Gajdosova beat German Andrea Petkovic 6-1, 7-6 (7-5); Chinese Peng Shuai came back to best Russian Anastasia Pavlyuchenkova 1-6, 7-6 (7-1), 6-4; rising Spaniard Garbine Muguruza erased former French Open runner-up Sara Errani 6-0, 7-5; Czech slugger Karolina Pliskova dismissed Slovenian qualifier Polona Hercog 6-4, 6-4; and Spaniard Carla Suarez Navarro outlasted former Wimbledon runner-up Sabine Lisicki 6-3, 3-6, 7-6 (7-4).

The second round will be staged Tuesday, including matches for top-seeded Simona Halep, No. 2 seed Petra Kvitova, Radwanska and Kerber. The French Open runner-up Halep, fresh off her season-opening title in China last week, will take on Pliskova, while the Wimbledon champion Kvitova will encounter Peng and Radwanska will face Muguruza.

This week's winner will take home $124,000.