Top male badminton stars -- K Srikanth and Parupalli Kashyap -- also entered the last four stage of the tournament by winning their respective matches.
Olympic bronze medallist Saina defeated compatriot Arundhati Pantawane 21-18 21-17 at the Babu Banarasi Das Indoor Stadium.
The top seed will next take on fourth seed Nichaon Jindapon of Thailand, who beat India's P C Thulasi 21-16 20-22 21-12 in another match that lasted one hour and six minutes.
Two-time World Championship bronze medallist, Sindhu too notched up a hard-fought victory over sixth seed Porntip Buranaprasertsuk of Thailand 8-21 21-11 21-14 to reach the final four. She will meet reigning World Champion Carolina Marin of Spain tomorrow.
World No. 5 Srikanth also continued his run and entered the semis after Malaysian fifth seed Wei Feng Chong retired after the second game with the score reading 17-21 21-12.
The China Open winner will next take on compatriot H S Prannoy, who clinched the Indonesia Masters last year. The fourth seed saw off another Indian R M V Gurusaidutt, seeded eighth, 21-18 21-19 in his quarterfinal match.
Third seed Kashyap who had won the men's singles title in 2012, defeated Singapore's Zi Liang Derek Wong, seeded 10th 21-18 21-9 in just over half an hour.

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