GLASGOW, Aug 25 — China's Chen Long and Spain's Carolina Marin, the men's and women's champions, progressed smoothly into the quarterfinals of the BWF World Championships in Glasgow yesterday.

Fifth-seeded Chen needed 41 minutes to quell the challenge of India's 13th seed Ajay Jayaram 21-11 21-10, while the third-seeded Marin saw off Denmark's Mia Blichfeldt 21-7 21-11.

Chen next takes on 10-seeded compatriot Tian Houwei, who got past France's Brice Leverdez 21-14 21-8. Olympic champion Marin set up a clash with Japan's seventh seed Nozomi Okuhara.

China's Lin Dan ran into more trouble a day after he dug deep to beat Denmark's Emil Holst. The seventh seed lost the first game but showed steely resolve to down England's Rajiv Ouseph 14-21 21-17 21-16.

Top seed Son Wan-ho survived a mid-match scare but was too powerful for Tanongsak Saensomboonsuk, winning 21-14 17-21 21-13. His opponent in the quarterfinals is India's Kidambi Srikanth.

Denmark's third seed Viktor Axelsen began proceedings at the Emirates arena in the morning with a clinical 21-17 21-13 win over Hong Kong's Ng Ka-long in 38 minutes.

Among the women, top seed Akane Yamaguchi's campaign came to a grinding halt when she lost to China's world junior champion Chen Yufei 21-18 21-19 in under an hour.

India's Pusarla Sindhu advanced at the expense of Hong Kong's Cheung Ngan-yi and faces China's Sun Yu next. Sindhu's compatriot Saina Nehwal beat second seed Sung Ji-hyun 21-19 21-15. — Reuters