London Olympics bronze medallist Saina thrashed Macau's Teng Lok U 21-10, 21-8 in 26 minutes while two time World Championships bronze medallist Sindhu took only 19 minutes to register a convincing 21-7, 21-13 win over Kit Leng Wong of Macau.
Saina, who shifted her training base from Hyderabad's Pullela Gopichand Academy to Bangalore under former national head coach Vimal Kumar before the Asiad, looked in fine form and started positively taking the first game 21-10 in 13 minutes.
In the second game, Saina, ranked seventh in the world, continued her dominance over Lok U and raced to a 13-4 lead and never looked back, finally winning the game 21-8.
The 24-year-old Saina will Thursday play Iran's Soraya Aghaeihajiagha for a place in the quarter-final.
In the match between Sindhu and Leng Wong, the World No.10 Indian proved too strong for Leng Wong, who is ranked 34th.
Sindhu didn't allow her opponent to settle at all, winning the first game 21-7 in just nine minutes.
In the second game, Leng Wong improved her performance and few mistakes from Sindhu helped the Macau shuttler put up a better fight.
But Sindhu kept playing her aggressive game to pile further pressure on Leng Wong, who in the end lost 13-21.
In the pre-quarter-finals to be held Thursday, 19-year-old Sindhu will take on Indonesia's Bellaetrix Manuputty, who defeated Nepal's Nangsal Tamang 21-5, 21-17.