Former world number one Zhang Ning of China defeated world champion Camilla Martin of Denmark at the Japan Open badminton tournament on Thursday.

The unseeded 25-year-old, who plans to hang up her racket next season, stormed back from a disastrous first game to score a 1-11, 11-8, 11-7 success over the Danish top seed in the women's singles second round.

In the quarter-finals Friday, Zhang will take on fifth seed Julia Mann of England, who comfortably advanced after Japan's Miho Tanaka abandoned the match at 0-2 in the second game.

Indonesia's Roni Agustinus caused another upset by eliminating Sydney Olympic and defending Japan Open champion Ji Xinpeng of China in the men's singles second round.

Other favourites, Peter Gade Christensen of Denmark, last year's All England champion Xia Xuanze of China, Swiss Open winner Muhammad Roslin Hashim of Malaysia in the men's, China's Zhou Mi and Gong Ruina all went safely through.

(People's Daily 04/05)