China's Zheng Jie (L)/Yan Zi celebrate their victory after the women's doubles quarter final match against Serena Williams/Venus Williams of the United States at the Australian Open tennis tournament in Melbourne, Australia, Jan. 22. They won 2-1. - Xinhua

Venus and Serena Williams, one of the favorites in the Australian Open, was beaten from the women's double by Chinese pair Zheng Jie and Yan Zi 6-3, 4-6, 2-6 in the quarterfinals yesterday.

"This is a big win for us." said Yan Zi, who won the Australian Open women's double title with Zheng Jie in 2006.

"We didn't expect win them before the match, but after the first set, we thought we had the chance to take the match." added Yan.

Serena Williams, defending champion in the women's singles but was downed by Jelena Jankovic early on Tuesday, paired with her elder sister to win the first set at 6-3.

The following two sets were merely the sole performance of the Chinese pair as they took the second and third sets in a row to enter the final four of the tournament.

"Williams sisters powerful serving caused us much trouble." said Zheng, "but I think we had some good returns in the second and third sets."

"This is a unexpected win, which will give up much confidence, especially when we want to go something good in the Olympics this year." said Zheng.