Igarashi produced a superb performance as he recovered from losing the opening game to clinch a surprise 16-21, 21-16, 21-18 success at the Singapore Indoor Stadium.

The 23-year-old's reward is a meeting with China’s Qiao Bin, who overcame Praneeth's compatriot RMV Gurusaidutt 21-14, 21-19.

The result ensured Praneeth's title defence ended at the first hurdle, with the sixth seed admitting his huge disappointment at failing to progress.

"I thought I would’ve won this match but my confidence is low," he said. 

"I was under pressure and started losing points and the points started going the other way so it felt really bad for me."

Elsewhere in the men's singles draw, top seed Chou Tien Chen of Chinese Taipei and number two seed Ng Ka Long of Hong Kong both booked their place in the second round.

Chou dispatched Sony Dwi Kuncoro of Indonesia 21-16, 21-16, while Ng faced a tougher task as he beat England's Toby Plenty 17-21, 21-14, 21-14.

The shocks continued in the women's singles tournament as third seed Beiwen Zhang of the United States fell to a 15-21, 21-11, 21-16 defeat to Chinese youngster Cai Yanyan.

Michelle Li of Canada, seeded fourth, avoided the same feat by ousting Indonesia’s Lyanny Alessandra Mainaky with a hard-fought 19-21, 22-20, 21-17 victory.

"She was getting all the shuttles back and I felt pressure, especially playing with the wind," said Li. 

"I was also feeling a little tired at the start but the crowd helped me."

The tournament in Singapore continues tomorrow.