Two-time champion, Saina Nehwal and HS Prannoy have advanced to the singles semi-finals at the Swiss Open Grand Prix Gold badminton tournament at Basel.Two-time champion Saina win over Japan's Sayaka Sato, seeded seventh.The Olympic bronze medallist will next take on her fierce rival Wang Yihan, seeded 3rd.Saina has a 4-9 record against the former World No. 1 but the top seeded Indian will take confidence from her three wins against the Chinese in 2015.In men's singles, 13th seed Prannoy will next face Tzu Wei Wang of Chinese Taipei.