Sindhu was a little circumspect during the match and committed a few unforced errors before surpassing Thailand's Busanan Ongbumrungphan 17-21 21-19 21-16 in a women's singles match that lasted an hour and 16 minutes here.
She will next take on Korea's Bae Yeon Ju, who beat Japan's Yui Hashimoto 21-16 21-10 in another match.
Later in the day, Saina saw off Nitchaon Jindapol of Thailand 21-19 21-14 to set up a clash with Korean fifth seed Sung Ji Hyun.
While Korea's Son Wan Ho stunned the six-time All England champion Lin Dan of China, seeded fourth, 21-13 22-20, former World no. 1 Lee, top seed, suffered a 19-21 19-21 loss to Hong Kong's Wei Nan, ranked World No. 14. Two more top 10 players bite the dust in men's singles at the Siri Fort Sports Complex here.
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While Xue Song saw off Denmark Jan O Jorgensen, seeded 3rd, 21-18 15-21 21-14 to emerge as the only surviving Chinese in men's singles, Germany's Marc Zwiebler stunned Chinese seventh seed Tian Houwei, who had reached the finals of the All England Championship, 18-21 21-19 23-21 in a thrilling contest in the men's singles.
In women's doubles, Mohita Sahdev and Sanjana Santosh defeated compatriot Ch Poornima and Rachita Sahdev 21-16 21-7.
They will meet Japanese combo of Naoko Fukuman and Kurumi Yonao.
Manu Attri and B Sumeeth Reddy suffered a 19-21 12-21 loss to Chinese Taipei's Chen Hung Ling and Chi-Lin Wang, while Jishnu Sanyal and Shivam Sharma lost 17-21 15-21 to Chinese Taipei's Lee Sheng Mu and Tsai Chia Hsin in another men's doubles match.
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The Indian came up with a couple of smashes to draw parity at 17-17. With Busanan finding the net and then hitting wide meant Sindhu had a two-point lead at 20-18. The Indian hit one at the net but roared back into contest when her rival found the net.
After the interval, Sindhu started dominating the proceedings and grabbed an 18-15 lead before another wide shot broke the rhythm. A fierce rally then ended with an unforced error from the Thai player. Sindhu then grabbed the next two points when Busanan failed to connect a couple of strokes at the forecourt.
"It was a close match and it is good to have a tough opponent early in the tournament because it helps you to adjust with the conditions. I was playing her after a long time and I made lot of unforced errors. I was leading and then giving away points. Even some line judgements were not right. I am happy to win and hope to play better tomorrow," Sindhu told reporters.
Jindapon continued to extend her lead before Saina clawed back at 15-15 with a powerful smash which her rival ended up buring at the net. The duo moved neck and neck till 19-19 before Saina grabbed the advantage with a soft return which Jindapon failed to negotiate. She then pocketed the game with a lightening smash.
Among others, Second seed Kento Momota of Japan defeated Hong Kong's NG Ka Long Angus21-16 21-11, while Denmark's Hans-Kristian Vittinghus notched up an upset win over Chinese Taipei's Chou Tien Chen, seeded sixth, 21-12 21-12 in another men's singles match.
In women's singles, Sixth seeded Chinese Wang Shixian saw off Japan's Sayaka Sato 19-21 21-11 21-14, while former world No. 1 Chinese Li Xuerui, seeded 3rd, went past a fighting Porntip Buranaprasertsuk of Thailand 17-21 21-13 23-21 in a 54-minute clash.