World No 3 Srikanth recovered from a lop-sided opening game to struggle past France's Brice Leverdez, ranked 23, 7-21 21-14 22-20, while Olympic and world championship silver medallist Sindhu staved off a stiff challenge from Thailand's Pornpawee Chochuwong to prevail 20-22 21-17 21-9 in a 56-minute contest.
Srikanth will square off against either China's Huang Yuxiang or England's Rajiv Ouseph, while Sindhu faces the winner of the match between USA's Beiwen Zhang and Thailand's Nitchaon Jindapol.
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.
Srikanth was no match for Leverdez in the first game as he failed to execute his strokes properly with most going wide and long. After a pep talk with coach Pullela Gopichand, Srikanth came back strongly in the second game.
He looked more aggressive and his approach earned him dividends as he forced the match into decider after winning 21-14.
In the third game, Srikanth was comfortably placed at 11-6 but Leverdez made fantastic recovery to make it 12-12. The duo fought hard and moved neck and neck till 18-18. Leverdez then won a long rally to grab a 19-18 advantage but Srikanth drew parity.
The Frenchman held a match point but the Indian once again levelled par and grabbed a match point, before managing to convert it.
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. She went to the 20-18 game point advantage before Sindhu clawed back but in the end it was the Thai shuttle who pocketed the game.
Jolted by the reversal, Sindhu surged to a 14-6 and 15-7 lead in the next two games and didn't lose control despite some spirited fight by Pornpawee.
Among others, Ashwini Ponnappa and N Sikki Reddy lost 14-21 13-21 to second seeded Japanese combo of Misaki Matsutomo and Ayaka Takahashi, while Jakkampudi Meghana and Poorvisha S Ram went down 14-21 11-21 to fifth seeded Japanese combo of Shiho Tanaka and Koharu Yonemoto 21-14 21-11 in women's doubles.
Men's doubles pair of Manu Attri and B Sumeeth Reddy also suffered a 20-22 12-21 loss against English combo of Marcus Ellis and Chris Langride to crash out.
Saina Nehwal exited from the prestigious tournament after suffering a straight-game defeat against World No. 1 and defending champion Tai Tzu-Ying....