CANBERRA, Jan. 13 (Xinhua) -- Top-seeded Serena Williams and second seed Dinara Safina went through second-round in ease Tuesday to move into the Sydney International quarterfinals.

    Williams, who was stretched to three sets and saved four match points in her opening match against Samantha Stosur of Australia, beat Sara Errani of Italy 6-1, 6-2 in 50 minutes.

    Safina finished off a 6-3, 6-0 win over fellow Russian Vera Dushevina in just over an hour.

    Four other seeded players in the women's draw at the joint ATP-WTA tournament also advanced Tuesday.

    No. 3 Elena Dementieva of Russia beat Jarmila Gajdosova of Slovakia 6-2, 6-4 and No. 5 Svetlana Kuznetsova of Russia beat Estonia's Kaia Kanepi 6-2, 2-6, 7-6 (7-3).

    Sixth-seeded Agnieszka Radwanska of Poland defeated Slovakia's Daniela Hantuchova 6-3, 7-5 and Caroline Wozniacki of Denmark, the eighth-seeded player, beat Britain's Melanie South 6-2, 6-0.

    Williams will play Wozniacki in the quarterfinals.

    In another match, Japan's Ai Sugiyama beat Anabel Medina Garrigues of Spain 2-6, 6-1, 6-2.

    In first-round men's play, Janko Tipsarevic of Serbia defeated eighth-seeded Mardy Fish of the United States 6-4, 3-6, 6-4; former No. 1 Lleyton Hewitt of Australia continued his comeback from a five-month injury layoff to beat Frenchman Julien Benneteau5-7, 6-2, 6-4 and Paul-Henri Mathieu of France beat Italian Andreas Seppi 6-2, 2-6, 6-3.

    The top four men's seeds received first-round byes. Djokovic, who begins the defense of his Australian Open title next week in Melbourne, plays Mathieu on Wednesday.