NANJING (AFP) - Viktor Axelsen and Nozomi Okuhara stormed into the third round to stay on course for back-to-back men's and women's titles at the badminton World Championships on Wednesday (Aug 1).

Denmark's Axelsen, the top seed and world No. 1, subdued a spirited first-game challenge from China's unseeded Huang Yuxiang before winning 21-17, 21-8.

Women's eighth seed Okuhara of Japan made even shorter work of unseeded Rachel Honderich, sending the 22-year-old Canadian packing 21-11, 21-9 in just 28 minutes in Nanjing.

The day's biggest shock was 11th-seeded Indian H.S. Prannoy's 8-21, 21-16, 21-15 defeat by little-known world No. 39 Brazilian Ygor Coelho.

Hosts China, led by the great Lin Dan, are the sport's superpowers, but they have seen their dominance slip of late and can expect a tough fight against the rest of the world's best in Nanjing.

It was so far so good in Wednesday's early matches as Olympic champion Chen Long dispatched Khosit Phetpradab of Thailand, 21-16, 21-11.

But Chen's compatriot, women's fifth seed Chen Yufei, had a rougher time against Gregoria Mariska Tunjung of Indonesia.

After Chen won the first game 21-17, Tunjung jumped into a 17-10 lead in the second and looked ready to extend the match to a third game.

But Chen, 20, stormed back to take the game 22-20 and win the match.

"I think I'm better prepared today, mentally and technically, and this makes me more confident," she told state-run Xinhua news agency.

The 34-year-old home favourite Lin, widely regarded as the best player of all time but seeded only ninth in Nanjing, faces off later against Sameer Verma of India.

In the men's doubles, Malaysians Aaron Chia and Soh Wooi Yik upset the 12th seeds from Chinese Taipei Lee Jhe-huei and Lee Yang 16-21, 21-18, 21-19.