The world No 4 has won her home tournament twice, in 2013 and 2017, but was forced to skip this edition due to a back injury she has been struggling with for two weeks.

“She has been advised by a doctor to take a break,” said her coach Patapol Ngernsrisuk, adding that the injury wasn’t serious but required rest.

Former world No 1 Ratchanok showed signs of injury in her Indonesia Open quarter-final against Sung Ji Hyun on Friday, losing 21-12 21-12.

“It’s difficult for her to play the forehand. If she entered the competition this week, she would risk tearing muscles,” Patapol added.

Ratchanok’s focus now will be on the World Championships in Nanjing and the Asian Games in Indonesia, both in August.

Without Ratchanok, Thai hopes in Bangkok will be shouldered by world No 11 Nitchaon Jindapol, No 19 Pornpawee Chochuwong and |No 30 Busanan Ongbamrungphan.

Today’s first round sees sixth seed Nitchaon play Soniia Cheah of Malaysia, while Pornpawee will take on Beatriz Corrales of Spain. Busanan has an easier opener after  fifth seed and 2012 winner Saina Nehwal of India withdrew. She will face Sabrina Jaquet of Switzerland instead.The top two women’s seeds are world No 2 Akane Yamaguchi of Japan and No 3 Pusarla V Sindhu.

Kantaphon Wangcharoen 

With world No 4 Shi Yuqi of China, No 5 Kidambri Srikanth of India and world No 7 and reigning Olympic champion Chen Long withdrawing, Prannoy H.S. of India, No 14 in the world, is the highest ranked player in the men’s singles.

In-form Kantaphon Wangcharoen, who should become Thailand’s new No 1 later this week after reaching the Super 1000 quarter-finals in Jakarta on Friday, is the country’s main hope in the men’s singles. He will open his campaign against a qualifier.

The Kingdom’s top mixed doubles pair of Dechapol Puavaranukroh and Sapsiree Taerattanachai are the other big home hopes this week. Seeded seventh, they play Taiwan’s Lee Yang and Hsu Ya Ching in the first round.