The London Olympics bronze medallist beat world No. 73 Brazilian Vicente Lohaynny 21-17, 21-17 in 39 minutes, while Sindhu, a two-time World Championships bronze winner, had things her way against Laura Sarosi of Hungary, winning 21-8, 21-9 in 27 minutes.
The Indian contingent's schedule at the Rio Olympics for Thursday.
Check out India's report card on the sixth day of the 2016 Olympics.
The shuttlers led by Saina Nehwal will make their first appearance in the Olympic Games on Thursday along with men golfers as India still waits for its first medal after five days of fruitless labour in this Brazilian city.
Adapting to the conditions in Rio and changing on-court strategy in match situation will be the key to success, according to ace Indian shuttler P V Sindhu, who is aiming to add an Olympic medal to her two World Championship bronze medals.
World No. 11 Kidambi Srikanth overcame some stiff resistance in the second game from lower ranked Mexican rival Lino Munoz before winning his Group H clash in straight games in the badminton singles event at the 2016 Olympic Games in Rio de Janeiro, on Thursday night.