France's Brice Leverdez stunned Malaysia's second seed Lee Chong Wei 21-19, 22-24, 21-17 in the first round of the BWF World Championships in Glasgow on Tuesday.
Leverdez, the world number 31, scored only his second win over Lee in nine matches and said playing without fear helped him in the 75-minute contest at the Emirates Arena.
"I know I am the underdog when I play Lee and usually I would have put pressure on myself. This time I wanted to play my game, joke on court with myself," the 31-year-old said.
Leverdez failed to convert two match points in the second game but kept his composure against a nervy Lee in the decider to grind out the result.
Defeat ended the 34-year-old Lee's hunt for an elusive first title in a competition in which he has been runner-up three times.
"Brice played so well today... he had the lead for a lot of the second game and he was very lucky," Lee said after the match.
Defending champion Chen Long started his campaign with a convincing win over Georges Julien Paul from Mauritius. The Chinese fifth seed downed his opponent 21-7, 21-9 in 29 minutes.
Taiwan's Chou Tien Chen survived a scare from England's Toby Penty before winning in three games while Denmark's Hans-Kristian Vittinghus lost to Chinese 10th seed Tian Houwei.
In the women's draw, Japanese top seed Akane Yamaguchi beat Denmark's Line Hojmark Kjaersfeldt 21-6, 21-13 in 30 minutes while fourth-seeded Indian Pusarla Sindhu beat South Korea's Kim Hyo Min 21-16 21-14.
China's Sun Yu, seeded fifth, powered past unseeded Indonesian Lyanny Alessandra Mainaky 21-13, 21-9 in 47 minutes. She was joined in the second round by compatriot Chen Yufei.
Thailand's Ratchanok Intanon overcame Malaysia's Rui Chen Yap 21-12, 21-7 while China's Chen Xiaoxin defeated Canada's Michelle Li 21-13, 27-25.
Image: Malaysia's Lee Chong Wei
Photograph: Chris Hyde/Getty Images