Australia's Samantha Stosur suffered a setback to her Australian Open preparations after going down to Jie Zheng in the opening round of the Apia International Sydney on Monday.
Stosur, the ninth seed at the Australian Open, lost 6-3 6-7 (7-9) 6-4 to China's world number 26 Zheng in two hours and 43 minutes.
Zheng saved seven of 11 break points, while Stosur won just 58 percent of points on her first serve and was left to rue four double faults.
Stosur, who bowed out in the first round of the Brisbane International last week, has now lost five consecutive matches on home soil dating back to Brisbane last year.
Meanwhile, third seed Sara Errani and fourth seed Li Na both advanced to the second round in straight sets.
Italy's Errani accounted for Czech qualifier Karolina Pliskova 6-1 6-3 in just 51 minutes, while China's Li needed more than two hours for a 7-6 (7-2) 7-5 win over American Christina McHale.
"It's very tough because in China it was like five or six degrees, but here it's over 30," Li said.
"Yesterday my coach told me the most important match was today, because today it wasn't really about technique, it was challenging my mind to show how strong I am on the court."
In other matches, Russia's former world number two Svetlana Kuznetsova, in just her second event since missing six months with a knee injury, defeated Germany's Julia Goerges 3-6 6-3 6-3.
"To beat a player as good as Julia right now is amazing," Kuznetsova said.
"I missed some easy forehands and didn't serve too well in the first set but I'm happy I improved in the second and third sets."
Russia's eighth seed Nadia Petrova went down 7-5 7-5 to Italian Roberta Vinci, while Serbia's Jelena Jankovic beat Austrian Tamira Paszek 6-2 7-6 (7-5).
American Madison Keys stunned Czech world number 17 Lucie Safarova 6-2 6-1, and Kazakhstan's Galina Voskoboeva ousted Belgian Yanina Wickmayer 3-6 7-6 (7-5) 6-2.
Kimiko Date-Krumm brushed aside local hope Casey Dellacqua 6-4 6-1, while fellow Japanese Ayumi Morita eliminated Slovakian Daniela Hantuchova 1-6 6-3 6-3.
In the men's draw, Spain's eighth seed Marcel Granollers survived a scare before beating Australian Matthew Ebden 5-7 7-5 6-1 to advance to the second round.
Germany's fifth seed Florian Mayer served four aces and won 86 percent of points on his first serve for a 6-1 6-2 victory against Portuguese qualifier Joao Sousa.
Frenchman Julien Benneteau clinched a 6-3 5-7 6-2 win over Spaniard Pablo Andujar, who bowed out despite saving 10 of 18 break points, including four match points at 4-5 in the second set.
Finally, Uzbekistan's Denis Istomin saved nine of 10 break points for a 6-7 (4-7) 6-4 7-6 (7-3) win over local wildcard James Duckworth.