PV Sindhu, who was playing competitive badminton for the first time since the All England Open in March last year, was rusty in the opening exchanges.
The Rio 2016 silver-medallist, though, got into her groove gradually as she went long with her serves and was on the attack against 23-year-old Blichfeldt.
To her credit, the Dane kept up the intensity against PV Sindhu but the Indian went into the break with an 11-7 lead.
PV Sindhu then decided to stretch her opponent with some cross-court play and forced Blichfeldt into errors while she herself retrieved most returns using her long reach to wrap up the first game soon.
The second game proved to be a tougher outing for the Indian badminton star. Though the initial points were closely contested, PV Sindhu decided to continue her long cross-court strategy and it paid as she went into the break leading 11-8.
However, Blichfeldt, after a short chat with her coach during the break, came out determined to not allow PV Sindhu to build any sort of momentum as she countered very well.
PV Sindhu used her experience to stay ahead of her opponent but Blichfeldt ran toe-to-toe to keep up and a couple of line judgment errors from Sindhu allowed the Dane enough room to force the match into a decider.
Blichfeldt used that momentum well in the third game as she forced PV Sindhu into being defensive and it paid off as the Indian made several errors to go into the break trailing 11-6.
The Dane continued to attack relentlessly as PV Sindhu was unable to gather herself and looked off the boil thereafter as Blichfeldt comfortably won with a series of cross-court winners.
"I can say that it was not my day because I played really well in the first game. In the second game, I should have finished it but there were some unforced errors on my side," Sindhu said after the match.
Sai Praneeth bows out
Sai Praneeth, who was also playing for the first time since March, was off the pace with his attacking game as Wangcharoen focused on keeping his returns in to win points consistently.
The Indian badminton player could not find the decisive smashes when needed as he conceded the first game in just 17 minutes.
Sai Praneeth competed better in the second game but struggled to build any momentum with his play, with Wangcharoen remaining calm enough to gather his points and close out the match in a little over half an hour.
Both Sindhu and Sai Praneeth had to make do without a coach as the Badminton World Federation (BWF)’s COVID rules dictated that no support staff could accompany a player if a member from their contingent had tested positive.
Among the Indian camp, Saina Nehwal and HS Prannoy had tested COVID-positive earlier in the day and withdrew from the event while Saina’s husband Parupalli Kashyap was also asked to quarantine and withdraw as he was in close contact.
Rankireddy/Ponnappa grind out win
The mixed doubles pair of Satwiksairaj Rankireddy and Ashwini Ponnappa began the day well after a tough three-game win in the Round of 32 against sixth-seeded Indonesians Hafiz Faizal and Gloria Emanuelle Widjaja.
Rankireddy-Ponnappa won 21-11, 27-29, 21-16 in a match that lasted an hour and 12 minutes.
The Indian badminton duo were both aggressive with their smashes and cheeky with the drop shots and although there were occasional moments of miscommunication, saw the tough periods through to progress to the pre-quarterfinals.
However, Ashwini Ponnappa was not able to make it two wins in a day as she was knocked out of the women's doubles with partner N Sikki Reddy after a 21-16, 21-7 loss to the fourth-seeded South Korean pair of Kim So Yeong and Kong Hee Yong.
For more updates on the Indian contingent, follow our Thailand Open live blog.
Lead Photo: Badmintonphoto - Courtesy of BWF.