World No. 1 Viktor Axelsen of Denmark clinched his opening win at the China Open by defeating Indonesian contender Chico Aura Dwi Wardoyo 21-17, 21-18 on Tuesday.
Men's doubles top seeds Fajar Alfian and Muhammad Rian Ardianto of Indonesia were stunned by the Danish duo Kim Astrup and Anders Skaarup Rasmussen 21-19, 21-19.
Olympic champion Axelsen has extended his record against Wardoyo to 4-0. "Changzhou is a great city and I am very happy to be here again. I am also very happy to win my first match," said Axelsen, who will meet Wang Tzu-wei of Chinese Taipei in the round of 16.
Axelsen's compatriot Anders Antonsen beat Lakshya Sen of India 23-21, 16-21, 21-9 to progress, and will face Singapore's seventh seed Loh Kean Yew, who eliminated Frenchman Christo Popov in 47 minutes.
Fifth seed Jonatan Christie of Indonesia knocked out China's Weng Hongyang 22-20, 19-21, 21-10 to book a last-16 berth.
"The loss is a lesson for me. I hope I will know how to turn pressure into motivation," said the Chinese shuttler.
In the women's singles, title favorite An Se-young of South Korea smashed Denmark's Mia Blichfeldt and will next take on China's Wang Zhiyi.
China's Zhang Yiman stormed into the last 16 after beating Busanan Ongbamrungphan of Thailand 21-18, 21-14, and will play against fourth-seeded Tai Tzu-ying of Chinese Taipei.
Home favorites Liang Weikeng/Wang Chang and Liu Yuchen/Ou Xuanyi both advanced in the men's doubles.
World No. 1 women's pair Chen Qingchen and Jia Yifan of China notched a dominating 21-18, 21-11 win against Indian duo Treesa Jolly and Gayatri Gopichand Pullela.
Another Chinese pair Zheng Siwei and Huang Yaqiong powered into the mixed doubles second round, and could play against South Korean pair Seo Seung-jae and Chae Yu-jung in the quarterfinal.
The China Open is another world-class badminton competition held in east China's Jiangsu Province after the Sudirman Cup in Suzhou in May.
Winners in five categories will be determined on Sunday.