In the men's draw, China's top ranked player Chen Long was defeated by Hong Kong's Ng Ka Long in the Super Series event, going down 21-14, 21-18.

The double world champion had needed three games in his first and second round victories and his luck finally ran out today.

Ng will now contest a semi-final with another non-seed, South Korea's Son Wan-ho, who battled past China's Tian Houwei 11-21, 21-15, 21-19.

China's second seed Lin Dan, the double Olympic champion, is now favourite for the title after he came through 21-18, 21-14 against Indonesia's Tommy Sugiarto.

Another Indonesian, Sony Dwi Kuncoro, continued his fine run by ousting China's Wang Zhengming 24-22, 12-21, 21-16.

The qualifier has now won a trio of three game matches in the main draw and will go up against Lin in the last four.

In the women's competition, Spain's top seed and two-time world champion Carolina Marin was beaten in three games by Japan's Akane Yamaguchi, 13-21, 21-18, 21-18. 

The Japanese will face Thailand's Malaysia and India winner Ratchanok Intanon, who kept her bid for three straight Super Series titles alive by knocking out compatriot Porntip Buranaprasertsuk 21-12, 21-18.

Defending champion Sun Yu kept her hopes of retaining the title alive by beating South Korean Sung Ji-hyun 21-15, 19-21, 21-19.

She will meet team-mate He Bingjiao who ended the hopes of American Zhang Beiwen, 21-16, 21-15.

The semi-finals will be played at the Singapore Indoor Stadium tomorrow.