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 to continue her winning streak to start 2013.
The fourth-seeded Li, who won the Shenzhen Open title 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.
The 30-year-old Chinese player will next meet Japanese qualifier Ayumi Morita, who ousted Slovak Daniela Hantuchova 1-6, 6-3, 6-3.
In an upset, American teenager Madison Keys ousted No. 17-ranked Lucie Safarova 6-2, 6-1.
Former No. 1-ranked Jelena Jankovic beat Tamira Paszek 6-2, 7-6 (5) to set up a showdown with unseeded Italian 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 6-1 6-3 and will go into a second-round match against Russia's Maria Kirilenko, 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 Australia's Casey Dellacqua 6-4, 6-1 and former U.S. Open and French Open winner Svetlana Kuznetsova continued her comeback from a knee injury that marred her 2012 season with a 3-6 6-3 6-3 win over Germany's Julia Gorges.
In men's matches, fifth-seeded Florian Mayer of Germany beat Portugal's Joao Sousa 6-1, 6-2 and Uzbekistan's Denis Istomin defeated Australian qualifier James Duckworth 6-7 (4), 6-4, 7-6(3).