Chou began the tournament, a BWF Grand Prix Gold event, at the St Jakobshalle in Basel as the top ranked men’s player following the withdrawal of number one seed Lee Chong Wei of Malaysia.

He had survived a second round scare on Tuesday but comfortable win yesterday seemed to have boosted his confidence.

The 26-year-old showed his ability again to claim the opening game 23-21 against Zwiebler.

The seventh seed immediately hit back, though, winning the second game 21-14 and maintained the momentum to complete the comeback, claiming the decider 21-19.

He will face the unseeded Swede Henri Hurskainen in tomorrow’s semi-final after China’s Xue Song withdraw from their quarter-final match.

In the other half of the draw, Tzu Wei Wang emerged as a 21-10, 21-17 winner in an all-Chinese Taipei quarter-final clash with Hsu Jen Hao

He will India’s H. S. Prannoy after he defeated Thailand’s Tanongsak Saensomboonsuk 21-18, 22-24, 21-9. 

The women’s third seed Wang Yihan progressed easily to the semi-finals after the Chinese star overcame Thailand’s Busanan Ongbumrungphan 21-13, 21-10.

She will now face India’s Saina Nehwal after the top seed recorded a 13-21, 21-15, 21-14 win against Japan’s Sayaka Sato.

Nehwal is the only player who can prevent China from claiming the women’s title after Sun Yu and He Bingjiao both recorded straight games wins in their quarter-final ties.

Sun brushed aside Thailand’s Porntip Buranaprasertsuk 21-7, 21-8, and her compatriot defeated India’s Pusarla V. Sindhu 21-13, 21-15.