China's Wang Yihan and Wang Xin, the top two seeds in the badminton women's singles draw at the London Olympics, won Monday to move into the knockout stage.
Wang Yihan, the reigning world champion, needed 41 minutes to beat Canada's Michele Li and reach the round of 16. Wang Xin took just 27 minutes to defeat American Rena Wang and move on.
Also in women's singles, fourth-seeded Saina Nehwal of India won her group after defeating Belgian Lianne Tan.
Malaysian Lee Chong Wei, the No. 1 men's singles seed, beat Finland's Ville Lang to reach the round of 16 in that tournament. Lin Dan, the second seed and defending gold medalist, also won to move on. Lin beat Lee in the 2008 Olympics final.
Ha Jung Eun and Kim Min Jung, the third seed in women's doubles, won their second match. On Tuesday they will meet the Indonesian pair of Meiliana Jauhari and Greysia Polii to decide their group's title.
China's Tian Qing and Zhao Yunlei, seeded second, also improved to 2-0 in women's doubles group play.
The No. 4 seed in men's doubles, Ko Sung Hyu and Yoo Yeon Seong of Korea, lost.
In mixed doubles, two seeded pairs improved to 2-0 in their respective groups -- No. 2 Xu Chen and Ma Jin of China, and No. 4 Joachim Fischer and Christinna Pedersen of Demark.
Group play ends Tuesday.