China's Chen Yufei in action at Badminton World Championships in Glasgow, Britain, Aug 22, 2017. [Photo/Agencies]

Chen Yufei, the junior world champion from China, beat women's No 1 Akane Yamaguchi of Japan 21-18, 21-19. It was Chen's first win in their four matchups, including losses this year in the Asian team championships and Australian Open. But Yamaguchi hasn't been a closer, and couldn't impose herself.

"I wasn't nervous at all," Chen said. Her reward was Ratchanok, the 2013 world champion.

Marin hardly broke a sweat again, and lined up Nozomi Okuhara of Japan, whom she has a 3-5 record against, and 1-1 this year.

Nehwal, the former No 1 chasing her first world title, took out second-seeded Sung Ji-hyun of South Korea 21-19, 21-15. She next faces inspired local Kirsty Gilmour, who lives 15 minutes away.

Another Indian, Olympic runner-up Pusarla Sindhu, will play Sun Yu of China in another quarterfinal.

AP