Kim Clijsters and Francesca Schiavone round winners on Sunday as the 2012 WTA World Tour season got underway at the Brisbane International tennis event.

Belgium's Clijsters, the fifth seed, had no problems in a 6-1, 6-4 victory over Romania's Simona Halep on the hardcourts at Queensland Tennis Centre.

Schiavone, the third seed out of Italy, was able to advance as her opponent, Ksenia Pervak, retired in the first set with an undisclosed injury.

Other winners on Sunday were Iveta Benesova of the Czech Republic, who took a 2-6, 7-5, 7-5 win over compatriot Lucie Safarova, and Bojana Jovanovski of Serbia, who defeated Australia's Casey Dellacqua 6-4, 6-2.

Top-seeded Samantha Stosur and Serena Williams both play on Monday.