Playing her first tournament since winning the bronze medal at the Tokyo Olympics in August, Sindhu couldn’t match her fifth seeded young Korean rival, going down 11-21 12-21 in 36 minutes.
Sindhu had also lost to An Seyoung in straight games the last time they clashed here two years ago in their only career meeting.
The reigning world champion, who had taken a break to rejuvenate after a hectic Olympics campaign, just couldn’t find a way across the attacking game of the Korean, who was always a step ahead during the contest.
An Seyoung made a superb start and took just six minutes to grab a massive seven-point lead at the break with Sindhu unable to find a crack in the Korean’s game.
The Indian tried to control the net but committed few unforced errors with the Korean showing great athleticism to return everything thrown at her.
The Korean dominated the forecourt and played some exceptional shots, including a few diving forehand returns, to lead 16-8. In the end, Sindhu netted to give 10 game points to the Korean, who sealed the opening game when the Indian erred again.
Sindhu tried to change her tactics by playing high lifts but she was not disciplined enough and after trailing 7-8 at one stage, she slipped to 8-11 at the break.
It was one-way traffic after the interval as An Seyoung jumped to 20-10 in a jiffy. Sindhu saved two match points before committing another error.
On Thursday night, India’s Sameer Verma notched up a stunning straight-game win over world no.3 Anders Antonsen to storm into the quarterfinals but it was curtains for Lakshya Sen at the Super 1000 tournament here.
World No 28 Sameer, who had qualified for the World Tour Finals in 2018 after winning three titles, produced a sensational performance to outwit local hero Antonsen 21-14 21-18 in a 50-minute men’s singles battle.
The 27-year-old from Madhya Pradesh will lock horns with 33-year-old Tommy Sugiarto, a bronze winner at the 2014 World Championships.
However, it proved to be too daunting a task for Lakhsya to match Olympic champion Viktor Axelsen as he thrashed the Indian 21-15 21-7 in a lop-sided second-round contest.
Coming into the match with a dismal 1-5 head-to-head count, Sameer showed great athleticism and tactical acumen to down Antonsen, a silver medallist at the 2019 World Championships.
Sameer opened a 2-0 lead before increasing it to 11-6 at the break.
The Indian kept his nose ahead, crushing all attempts by the Danish player to make a comeback. He comfortably sealed the opening game with three straight points.
The second game was slightly tighter but Sameer ensured that he held on to his two-point lead throughout after being 5-3 up early on.
Sameer entered the interval at 11-8 and didn’t allow Anderson to make any comeback.