Lee Zii Jia failed to progress beyond the German Open second round after the top seed lost 21-15, 20-22, 21-23 in a nail-biting encounter against Chinese Taipei’s Lee Chia-hao on Thursday.
The 57-minute defeat comes as another damaging blow for Lee, who was nowhere close to the confident shuttler he was just several months ago.
After losing to the opponent he was expected to beat comfortably on paper, Lee took to social media to vent his frustration, posting on Instagram Stories: "I'm f***ing done".
Without a coach and recently admitting he was in need of some much needed confidence, this setback came a week before he is set to compete at the All England.
Besides Lee, Goh Jin Wei also crashed out in the women’s singles following a 13-21, 10-21 defeat to Pornpawee Chochuwong.
Meanwhile, Chen Tang Jie-Toh Ee Wei ensured Malaysia would be represented in Friday's quarter-finals after the scratch mixed doubles pair took down sixth seeds Seo Seung-jae-Chae Yu Jung 21-11, 24-22 earlier in the day.
It was a huge victory that booked them a meeting with another South Korean pair in Kim Won-ho-Jeong Na Eun.