Men's singles top seed Lee Dong-keun is out of the Badminton World Federation (BWF) Canada Open in Calgary after losing to a qualifier in straight sets.
The South Korean was well beaten by Yu Sheng-po of Chinese Taipei, who triumphed 21-13, 21-5 at Markin MacPhail Centre.
Third seed Prannoy Haseena Sunil Kumar of India also crashed out in two sets, losing to Koki Watanabe of Japan, 21-16, 21-10.
It means the highest-ranked male player in the round of 16 is Chinese Taipei's fourth seed Wang Tzu-wei, who defeated Brazil's Ygor Coelho in a three-set battle, 21-15, 19-21, 21-19.
In the women's singles, top seed and home favourite Michelle Li came through against South Korea’s world number 59 Sim Yu-jin with a hard fought victory, 21-17, 19-21, 21-12.
She plays Taipei's Lin Hsiang-ti next.
The biggest seed to fall was South Korea's Kim Ga-eun, who was beaten by Germany's Fabienne Deprez after a gruelling duel, 19-21, 21-19, 22-20.
The Canada Open is due to run until Sunday (July 7) and has a total purse of $75,000 (£59,000/€66,000).
It is the third Super 100 event on this year’s BWF World Tour.