Top seeded Venus Williams was defeated by China's Li Na in a breath taking tie in the Women's Singles Australian Open.Li Na come from behind and upset Venus 2-6, 7-6 (7-4), 7-5. Li Na's memorable victory sparked huge interest in China with national broadcaster CCTV, newspaper and websites giving wide coverage.The semi-final line-ups have been drawn in both Men's and Women's Singles. In the Men's section, Frenchman Jo-Wilfried Tsonga will meet Swiss star Roger Federer, while fifth-seeded Andy Murray of Britain faces 14th seeded Croat Marin Cilic on Friday. In the women's semi-finals, American Serena Williams will take on Li Na of China and Justine Henin will clash with unseeded Chinese Zheng Jie.