Former champion Li Na advanced to the second round of the Sydney International with a 7-6 (2), 7-5 win over Christina McHale on Monday, and Sam Stosur extended her miserable start to 2013 with another first-round loss.
The fourth-seeded Li, who won the Shenzhen Open last week, started her breakthrough 2011 season with a title in Sydney before reaching her first Grand Slam final at the Australian Open, then winning her first major at Roland Garros. She has slipped slightly in the rankings but is coming back to conditions that suit her in Australia.
The 30-year-old Chinese player will next meet Japanese qualifier Ayumi Morita, who ousted Daniela Hantuchova of Slovakia 1-6, 6-3, 6-3.
The ninth-ranked Stosur lost 6-3, 6-7 (7), 6-4 to Zheng Jie of China, her fifth loss in as many matches on Australian soil dating to last season.
The 2011 U.S. Open champion will head to the season's first major at Melbourne Park next week with only two matches since minor ankle surgery six weeks ago.
In another upset result, American teenager Madison Keys defeated 17th-ranked Lucie Safarova of the Czech Republic 6-2, 6-1.
Former No. 1 Jelena Jankovic beat Tamira Paszek 6-2, 7-6 (5) to set up a showdown with unseeded Italian veteran Roberta Vinci, who upset eighth-seeded Nadia Petrova 7-5, 7-5.
French Open finalist Sara Errani advanced 6-1, 6-3 over Czech qualifier Karolina Pliskova and will go into a second-round match against Maria Kirilenko of Russia, a 7-5, 6-2 winner over Australian wild-card Olivia Rogowska.
In other first-round matches, 42-year-old Kimiko Date-Krumm of Japan beat Casey Dellacqua of Australia 6-4, 6-1 and former U.S. Open and French Open winner Svetlana Kuznetsova downed Julia Goerges of Germany 3-6, 6-3, 6-3 to continue her comeback from a knee injury that marred her 2012 season.
In men's matches, fifth-seeded Florian Mayer of Germany beat Joao Sousa of Portugal 6-1, 6-2, No. 8 Marcel Granollers of Spain had a 5-7, 7-5, 6-1 win over Matthew Ebden of Australia and Denis Istomin of Uzbekistan defeated Australian qualifier James Duckworth 6-7 (4), 6-4, 7-6(3).