Top seed Ana Ivanovic opened her 2009 season with a straight-sets defeat of Petra Kvitova at the Brisbane International.
The 21-year-old Serbian, who enjoyed a spell at the top of the rankings in 2008 before ending the year in fifth, was too strong for her Czech opponent and ran out a comfortable 6-4 6-2 winner.
Daniela Hantuchova was one of three seeds to crash out after losing to Italy's Sara Errani.
The tall Slovakian, seeded number four, started well but then collapsed to a 6-7 (1/7) 6-4 6-0 defeat.
Eighth seed Francesca Schiavone and ninth seed Ai Sugiyama also lost, Schiavone going down 7-5 6-2 to Olga Govortsova from Belarus and veteran Japanese Sugiyama falling 6-2 6-3 to home favourite Sam Stosur.
Stosur, ranked 52nd in the world, was due to play Russian Maria Kirilenko in the opening round before the seventh seed withdrew due to illness.
The Queenslander is aiming to get back to full fitness after suffering from Lyme disease and viral meningitis in 2007 which saw her ranking slip from a career-high 27.
Former world number one Amelie Mauresmo is through although she was pushed all the way by the returning Jelena Dokic.
Dokic, a Wimbledon semi-finalist in 2000, battled hard but the Frenchwoman prevailed 7-6 (11/9) 7-6 (7/5).
There were also wins today for Tathiana Garbin and Lucie Safarova.