World number one Caroline Wozniacki's preparations for the Australian Open suffered a major setback when she was knocked out of the Sydney International in her first competitive match of the year on Tuesday.
The 20-year-old Dane, who had received a bye through the first round, went down 6-3, 6-3 to Slovakia's Dominika Cibulova at a rainy Sydney Olympic Park.
Wozniacki, who won six tournaments last year to reach the pinnacle of the women's game, had lost to world number two Vera Zvonareva in a Hong Kong exhibition event before arriving in Sydney.
Russian Zvonareva and world number three Kim Clijsters are also in second round action on Tuesday at the warm-up tournament for the year's first grand slam, which begins at Melbourne Park next Monday.