Williams sisters reach quarter-finals

Williams sisters reach quarter-finals

Venus Williams and Serena Williams (L) of the United States celebrate their victory over China's Zheng Jie and Yan Zi during the women's doubles third round match at the 2009 Wimbledon Tennis Championships in London, Britain, on June 29 2009. The US pair won 2-0.

Venus Williams and Serena Williams (Rear) of the United States compete during the women's doubles third round match against China's Zheng Jie and Yan Zi at the 2009 Wimbledon Tennis Championships in London, Britain, on June 29 2009. The US pair won 2-0.

China's Zheng Jie (R) and Yan Zi react during the women's doubles third round match against Venus Williams and Serena Williams of the United States at the 2009 Wimbledon Tennis Championships in London, Britain, on June 29 2009. The Chinese pair lost the match 0-2.