Defending champion Saina Nehwal's hopes of retaining her Thailand Grand Prix Gold title went up in smoke as she suffered a shocking three-game defeat to Singapore's Juan Gu, while promising youngster K Srikanth entered the semifinals of the men's singles event in Bangkok on Friday.
Twenty-year-old Srikanth overcame South Korea's Wan Ho Son in straight games 21-17 21-18 to set up a clash against Thammasin Sitthikom of Thailand.
Saina, ranked number two in the world, however lost 21-13 12-21 18-21 to eighth seed Juan in a 53-minute match at the Nimitbutr National Stadium here. This was Saina's first defeat to the Singaporean in six encounters.
In the first game, Saina opened up a slender 4-2 lead but Juan continously put pressure on her and caught up with the Indian at 9-9. The 23-year-old from Hyderabad then registered two points to move into the breather with a two-point cushion.
Saina then slowly started widening the gap and accumulated points at will to pocket the first game.
World number 23 Juan came back strongly in the second round and turned the heat on Saina, moving into the break at 11-7. The China-born Singaporean didn't give Saina much chance to fightback and roared into the contest by pocketing the second game 21-12.
Saina began the decider with a 5-2 lead but Juan turned the tables soon to hold the advantage at 11-10. Saina once again bounced back to lead 15-13 but the Singaporean showed immense character in wresting back the lead at 19-15 before shutting the door on the Indian.
Meanwhile, HS Prannoy was send packing by Indonesia's Wisnu Yuli Prasetyo 21-12 21-19 in the other quaterfinal match of men's event.