Phittayaporn Chaiwan remains on course to win the women's singles event at the BWF World Junior Championships in Kazan ©BWF

Top seeds Kunlavut Vitidsarn and Phittayaporn Chaiwan remain on track to win the men's and women's singles events at the Badminton World Federation World Junior Championships after the Thais reached their respective semi-finals.

Vitidsarn, bidding for a third consecutive men's singles title, beat Indonesia's Bobby Setiabudi 17-21, 21-16, 21-14 in the last eight at the Kazan Gymnastics Centre in the Russian city. 

It sets up a penultimate-round encounter with another Indonesian, 13th seed Yonathan Ramlie, who defeated Malaysia's Shahyar Shaqeem 21-16, 17-21, 21-19.

The other men's singles semi-final pits China's Li Yun Ze against France's Christo Popov.

Li benefited from the withdrawal of injured Malaysian opponent Goh Wyman, while Popov overcame China's Ren Cheng Ming 16-21, 21-10, 21-13.

In the women's singles competition, Chaiwan moved through to the last four by beating Japan's Akari Kurihara 21-13, 21-17.

Standing between her and a place in the final is seventh-seeded Japanese Riko Gunji, a 21-12, 21-12 victor over fourth-seeded Indonesian Putri Kusuma Wardani.

Second seed Zhou Meng of China is also through to the semi-finals having defeated Indonesia's Stephanie Widjaja 21-7, 21-11.

Next up for her is fellow countrywoman Dai Wang, who overcame Chinese Taipei's Hung En-Tzu 21-13, 21-19.

Action in Kazan continues tomorrow.