Newly crowned women's world champion PV Sindhu was dumped out of the Badminton World Federation China Open by Thailand's Pornpawee Chochuwong on second-round day in Changzhou.
The Indian fifth seed was riding the crest of a wave after reaching the sport's summit at the World Championships in Basel last month, but was second best today.
Chochuwong showed great mental strength to battle back from behind and send Sindhu home, 12-21, 21-13, 21-19.
"Last month she won the World Championships but today I just gave my all and fought for every shot that we played," said the Thai, who is now into the quarter-finals at the Olympic Sports Center Xincheng Gymnasium.
"Today is a very good day for me.
"The draft was different at each end, a bit side to side.
"I played on the same court last night and that helped me today, so I just tried to control my shots."
Elsewhere, reigning Olympic champion Carolina Marin continued her revival after eight months out with an ACL injury.
In only her third match back, the defending China Open champion saw off United States player Zhang Beiwen 21-17, 21-12.
It followed her superb first-round win against Japan's fourth seed and 2017 world champion Nozomi Okuhara.
Russia's Evgeniya Kosetskaya, who stunned Japan's top seed Akane Yamaguchi in round one, could not repeat the trick as another Japanese player, Sayaka Takahashi, knocked her out with a 21-17, 21-15 win.
Chinese Taipei's second seed Tai Tzu-ying advanced by beating Japan's Aya Ohori 21-19, 21-14, and there was home delight for China's third seed Chen Yufei, a 20-22, 21-17, 21-15 winner against An Se-young of South Korea.
In the men's draw, Japan's back-to-back world champion Kento Momota made short work of Indonesia's Tommy Sugiarto as the top seed won 21-10, 21-11.
China's fifth seed Chen Long, the Rio 2016 Olympic gold medallist, came through against Chinese Taipei's Wang Tzu-wei 21-10, 21-17 as he targets a fifth title at his home event.
Defending champion Anthony Sinisuka Ginting of Indonesia continued his title defence as seventh seed, beating Parupalli Kashyap of India 23-21, 15-21, 21-12.
Second seed Chou Tien-chen of Chinese Taipei edged home hope Huang Yuxiang 21-19, 21-18, and Denmark's World Championship runner-up Anders Antonsen, seeded eighth, saw off compatriot Rasmus Genke 21-11, 21-15.
The quarter-finals at the World Tour Super 1000 tournament are tomorrow.