Tokyo: Ratchanok Intanon just can't seem to find a way to beat Chen Yufei.
The seventh seed from Thailand lost to the reigning junior world champion for the third straight time in the last-16 round of the US$325,000 Japan Open while all the other Thai players also exited the BWF Superseries tournament.
China's Chen, 19, needed only 38 minutes to win the encounter 21-15, 21-17 at Tokyo Metropolitan Gymnasium.
Chen rallied from a game down to beat Ratchanok at the World Championships in Glasgow last month. She also won the pair's first meeting at the 2016 Korea Open.
Today Chen takes on Aya Ohori, who won all-Japanese clash against Haruko Suzuki 21-17, 24-22.
Ratchanok is still looking to win her first Superseries title of the year. She has won two titles so far this season -- the Thailand Open in June and the New Zealand Open last month -- both Grand Prix Gold tournaments.
Bodin Isara and Savitree Amitrapai lost to Wang Yilyu and Huang Dongping of China 19-21, 17-21 in the mixed doubles, while Jongkolphan Kititharakul and Rawinda Prajongjai went down to eighth seeds Yuki Fukushima and Sayaka Hirota of Japan 12-21, 13-21 in the women's doubles.
In the men's doubles, the injured Bodin and playing partner Nipitphon Phuangphuphet were forced to retire at 22-22 in the second game against Denmark's Kim Astrap and Anders Skaarup Rasmussen. The Danes won the first game 21-16.
Meanwhile, Japan's world champion Nozomi Okuhara avenged her Korea Open final loss against India's PV Sindhu and moved into the last eight of her home tournament.
The world No.9 Okuhara, a bronze medallist at last summer's Rio Olympics, beat the fourth seed 21-18, 21-8.
Okuhara, who became the first singles world champion from Japan after defeating Sindhu in the final, next faces Zhang Beiwen of the US.
Second seed Akane Yamaguchi also advanced to the quarter-finals, beating South Korea's Kim Hyo-Min 21-12, 18-21, 21-8.
In the men's singles, Denmark's world champion and third seed Viktor Axelsen beat Japan's Kenta Nishimoto 21-17, 21-18 to claim a spot in the quarter-finals.