Saina Nehwal won the first game but was unable to build on it. Kidambi Srikanth, meanwhile, pulled out due to injury and Chirag-Satwik were also eliminated.
Saina Nehwal, who dominated in her first-round win over Kisona Selvaduray after a testing time the day before, began slowly as a few line misjudgments and weak shots allowed her opponent to build a 4-0 lead in the first game.
However, the Olympic bronze medallist clawed her way back soon enough, as she steadily maintained a mid-court base and tied the scores with some good rallies.
Ongbamrungphan, though, was alert to Saina Nehwal’s distance from the net and pulled off a few cheeky drop shots to go into the mid-game break leading 11-9.
The 30-year-old Saina did lose a couple of close points after the game restarted but her strong backhand and deceptive forehand winners allowed the Indian to take a 19-17 lead.
However, Ongbamrungphan drew level at 20-20 and even earned a game point at 21-20 but the Indian badminton player brought out her trademark dipping forehand shots to win three consecutive points and close out the first game.
Saina Nehwal was being coached on the sidelines by husband Parupalli Kashyap – who stayed back to help after he was forced to retire midway through his first-round match on Wednesday after pulling his calf muscle.
The second game began more positively for Saina Nehwal but Ongbamrungphan sensed her discomfort with moving around the court too much. As a result, the Thai shuttler went long with her serves, winning a series of points with her drop shots to lead 11-7 at the break.
Saina Nehwal then conceded a six-point lead to her Thai opponent but a long serve from Ongbamrungphan gave her the point she needed to build momentum and the Indian reeled off four points in a row to come back at 13-15.
A short water break allowed the 24-year-old Ongbamrungphan to gather her breath and resume her immaculate netplay as she won the next five points to earn a game point at 20-13 and a long forehand from Saina then gave her the second game.
The deciding game was another slow start for the Indian badminton star as she trailed early on before coming back into the game at 5-7 but went into the break at 7-11.
Saina Nehwal looked off the pace after that as her opponent steadily built her lead by prevailing in the rallies and won the match when Saina sent a forehand return wide of the baseline.
“I tried my best today, was definitely moving well. I tested positive for COVID in November, so the recovery took time and I did whatever preparation I could in three weeks. You need better endurance at the highest level,” Saina Nehwal said after the match.
The pair of Chirag Shetty and Satwiksairaj Rankireddy fell in the second round to second-seeded Indonesians Mohammad Ahsan and Hendra Setiawan 21-19, 21-17.
Chirag-Satwik, the reigning men’s doubles champions at the Thailand Open, battled well in the opening game but were unable to prevail in crucial moments.
The second game was more error-prone from the Indian badminton players and their world champion opponents duly punished those with powerful strokes and finished off the match with a body smash.
Satwiksairaj Rankireddy then suffered a second loss of the day as he and partner Ashwini Ponnappa fell 21-12, 21-17 to Hong Kong's Chang Tak Ching and Ng Wing Yung in the mixed doubles.
Meanwhile, former world No. 1 Kidambi Srikanth pulled out of the Thailand Open after he pulled his calf muscle.
Srikanth, who had beaten fellow Indian shuttler Sourabh Verma on Tuesday, was due to face Malaysian eighth-seed Lee Zii Jia in the pre-quarterfinals but it was not to be, bringing the Indian challenge to a premature end at the Thailand Open.
For play-by-play highlights of the Indian contingent, visit our live blog of Day 3 of the Thailand Open.