Olympic bronze medallist Saina Nehwal registered a14-21, 21-18, 21-12 victory over Sayaka Takahashi of Japan to enter the quarterfinals of the women's singles event of the World Badminton Championships, at Copenhagen today. World No. 7 Saina, seeded seventh in the tournament, will take on World No. 1 Li Xuerui of China in the last eight stage of the tournament.