Singapore Open champion B Sai Praneeth squandered an opening game advantage to go down 21-13 15-21 11-21 to fifth seed Korean Son Wan Ho.
Sindhu, on the other hand, blew a 11-4 advantage in the opening game as Pornpawee fought back to catch up with the Indian at 14-14.
In the third game, Srikanth was comfortably placed at 11-6 but Leverdez made fantastic recovery to make it 12-12.
Sindhu had early jitters as she conceded the first game after a tough fight, but clawed back in the next two without giving any chance to the Thai shuttler for a comeback.
Nehwal crashed out of the Championship after losing the contest in straight games 14-21, 18-21 in 38 minutes to defending champion, Tai Tzu Ying of Taiwan.
Sindhu recovered in time and wrapped up the game with the decider lasting just 15 minutes.
In women's doubles, India's Meghana Jakkampudi and Poorvisha Ram lost 14-21, 11-21 to fifth seed Shiho Tanaka and Koharu Yonemoto of Japan in their opening round match. Saina had reached the finals in the 2015 edition.
The Indian, however, grabbed three consecutive points after Tai Tzu erred with a cross court flick and netted the smash. Saina fought back brilliantly to level it at 10-10, before going to mid-game break 10-11.
With the Taiwanese sending the shuttle to the net on four occasions on the trot, Saina managed to lead 16-11. After that Saina lost the lead at 17-18, for the first time in the game, and Tai made sure that it did not slip away as she won the second game 21-18.