Sindhu, the 26-year-old two-time medallist at the Olympic Games and a World Champion, lost the first game but powered back to win the next two to beat Clara Azurmendi 17-21, 21-7, 21-12 in a 47-minute encounter in the BWF World Tour Super 750 event.
The 23-year-old Clara, a resident of Madrid, Spain, and who is currently ranked 56th in the World Rankings, started superbly and caught up with Sindhu at 9-9 after the Indian had taken a slight lead from 2-2.
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The scores went neck-and-neck till 14-14 before the Spanish player opened up a lead by winning four consecutive points and went on to win the game at 21-17.
Sindhu dominated the next game as she took an early lead and built on it to go 15-4 up, winning 10 consecutive points during the game. The 26-year-old from Hyderabad, who won a bronze medal at the Tokyo Olympic Games in August to add to the silver she bagged in Rio de Janeiro in 2016, won the second game 21-7, capitalising on the first game point.
Sindhu was again on top in the decider and after the initial exchanges, surged ahead to a 14-7 lead at one time as she won five consecutive points. She wrapped up the game and match at 21-12, capitalising on her superior play against her young rival from Spain.
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In the quarter-finals, Sindhu will take on Neslihan Yigit of Turkey, who defeated Marina Ulitina of Ukraine 21-18, 21-13 in the second round on Thursday.
Japan's top seed Akane Yamaguchi and Thailand's Pornpawee Chochuwong, the fifth seed here, too advanced to the quarter-finals. While Yamaguchi needed three games to beat South Korea's Kim Gaeun 21-17, 14-21, 21-16, the Thai player defeated Japan's Aya Ohori 21-13, 21-12 in second round encounters on Thursday.