Chinese players Li Ting and Sun Tiantian, who surprisingly entered the women's doubles semifinals at the US$6.5-million Nasdaq-100 Open at Key Biscyane, Florida, were forced to retire on Saturday due to Li's injury.

　　The Chinese pair lost the first set 4-6 to Russia's Nadia Petrova and American Meghann Shaughnessy, and had to quit in the second set when 40-30 up in the first game as Li strained her right leg.

　　Li and Sun, who knocked out the third-seeded duo of Russian Liezel Huber and Japan's Ai Sugiyama to reach the semis, began strongly on Saturday, leading 4-1 in the first set after grabbing the initiative by breaking their opponents' opening service game.

　　But the sixth-seeded Petrova and Shaughnessy came back immediately, taking five games in a row, including two on Li and Sun's break-points.

　　(Xinhua)