Local hopeful Ratchanok Intanon begins her campaign for a third Thailand Open title on Wednesday.
Ratchanok and mixed doubles duo Dechapol Puavaranukroh and Sapsiree Taerattanachai are seen as Thailand's best bets in the BWF World Tour Super 500 event at Indoor Stadium Hua Mark.
The US$350,000 (approximately 10.8 million baht) tournament offers qualifying points for the 2020 Olympic Games in Tokyo.
The event started yesterday with qualifying matches and some first round games.
Sixth seed Ratchanok will meet Yvonne Li of Germany in her opening match on Wednesday.
The 2013 world champion should have few problems and could face compatriots Nitchaon Jindapol or Busanan Ongbamrungphan in the second round.
Ratchanok, 24, is the only local star to have won the women's singles title at the Thailand Open with her triumphs in 2013 and 2017. She has won two tournaments this year.
Other contenders in the women's singles competition include Chinese top seed Chen Yufei, compatriot and fifth seed He Bingjiao, and seventh seed Saina Nehwal of India.
Fourth seeds Dechapol and Sapsiree, who are seeking their first Thailand Open crown, will play qualifiers Qu Xuanyi and Feng Xueying of China in the first round.
In the men's singles, Kantaphon Wangcharoen leads the Thai challenge and will face Sai Praneeth Bhamidipati of India in the opening round.
World No.16 Kantaphon is the highest-ranked Thai in the men's singles and could next face No.1 Kento Momota of Japan, who won the Japan Open on Sunday.
Reigning world champion Momota plays Indian Sabhankar Dey in the first round.
Suppanyu Avihinghanon has a tough assignment against five-time world champion and two-time Olympic winner Lin Dan of China.
The men's singles event also features Taiwan's Chou Tien-chen and China's reigning Olympic champion Chen Long.
In Tuesday's qualifying, newly-crowned Asian U19 champion Kunlavut Vitidsarn lost 21-19, 21-11 to Indonesian veteran Sony Dwi Kuncoro, the 2012 champion in Bangkok.
Tanongsak Saensomboonsuk, the 2016 Thailand Open winner, also failed to reach the main draw after losing to China's Ren Pengbo 21-17, 10-21, 12-21.
In the women's doubles first round, Jongkolphan Kititharakul and Rawinda Prajongjai beat Chow Mei Kuan and Lee Meng Yean of Malaysia 21-14, 21-17.
Puttita Supajirakul and Sapsiree Taerattanachai were defeated by top seeds Mayu Matsumoto and Wakana Nagahara of Japan 21-14, 13-21, 21-6.