Indonesia's Simon Santoso upset Malaysia's world No. 1 Lee Chong Wei 21-15, 21-10 on Sunday to win the OUE Singapore Open at the Singapore Indoor Stadium.

This is just the second time Santoso has beaten Lee in 11 meetings on the Badminton World Federation circuit. When they met at the 2008 Singapore Open final, Santoso was thrashed 13-21, 5-21.

Said Lee shortly after his shock loss in front of a near-capacity 9,500-strong crowd: "Simon played very well today, I've not seen him play so well in a long time."

Santoso, a former world No. 3 and two-time SEA Games champion, is now ranked No. 52 after a series of injuries kept him on the sidelines.

In the women's singles, China's world No. 3 Wang Yihan retained her title after beating team-mate Li Xuerui 21-11, 21-19.

Li, the world No. 1 and Olympic champion, gave the match away after making far too many unforced errors.

Said Wang: "Maybe I had better luck today too, but I think we both did very well."

With the Singapore Open serving as the last Superseries before next month's Thomas and Uber Cup finals, Wang said the results bode well for her preparations.

"Xuerui, (world No. 2) Wang Shixian and I have been splitting the wins at the major tournaments recently, so that is good for us. But Thailand and Japan still have very strong teams."

Mixed doubles pair Tontowi Ahmad and Liliyana Natsir retained their title after beating team-mates Riky Widianto and Puspita Richi Dili 21-15, 22-20.

Cai Yun and Lu Kai upset sixth seeds Lee Sheng-mu and Tsai Chia-hsin of Chinese Taipei in the men's doubles 21-19, 21-14 to win their first title as a pair together.

Said Cai, a veteran player who won the Olympic title in 2012 with Fu Haifeng: "Lu Kai has improved a lot although he was still very nervous at the start."

China's Bao Yixin and Tang Jinhua won the women's doubles title, beating Denmark's Christinna Pedersen and Kamilla Rytter Juhl 14-21, 21-19, 21-15.