The fourth-seeded Sindhu, a Rio Games silver medallist, took 39 minutes to get the better of world number 22 Mia Blichfeldt 21-13 21-19, her second straight win over the Danish shuttler, who had clinched the Spain Masters earlier this year.
World number 6 Sindhu will next face China's Cai Yanyan, a 2017 BWF World Junior Championships bronze medallist.
Sixth seed Saina, however, had to work hard in her bid to avenge a Malaysia Open first-round loss to Pornpawee Chochuwong before pulling off a thrilling 21-16 18-21 21-19 win over the Thai shuttler in the second round.
The London Olympic bronze medallist will next square off against second seeded Japanese Nozomi Okuhara.
Earlier in the day, Sindhu led throughout in the first game after opening up a 3-0 advantage but in the second game, she was locked in a tight battle with Mia till 8-8. The Indian was, in fact, trailing 11-15 at one stage.
However, Sindhu managed to claw back at 17-17 and then nosed ahead to seal the issue in her favour.
Sindhu had reached the semifinals of the India Open last month.
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