Kunlavut Vitidsarn got off to a strong start at the season-ending BWF World Tour Finals in Hangzhou, China, on Wednesday.
Olympic silver medallist Kunlavut claimed his opening Group B victory after he defeated Japan's Kodai Naraoka in two games in the men's singles event at the Hangzhou Olympic Center.
In a closely fought contest, Kunlavut edged his Japanese rival to take the first game 24-22.
Kunlavut raced to a 7-0 lead and widened the gap to 11-3 in the second game before Naraoka rallied to tie at 17-all. The Thai made another late push to claim the second game 21-18.
Kunlavut will face China's Shi Yuqi on Thursday in his second group match, knowing a win will guarantee his place in the semi-finals.
Shi survived a tough opener on Wednesday against Jonatan Christie as he edged the Indonesian star 21-16, 17-21, 21-8 in 64 minutes.
Earlier, Thai women's singles star Supanida Katethong fell to South Korea's An Se-Young 16-21, 14-21 in their women's singles Group B clash.
Finals debutant Supanida will have to beat China's Han Yue in her second match today to avoid an early exit from the US$2.5 million tournament. Han was impressive in her 21-19, 21-17 win over Japan's Akane Yamaguchi on Wednesday.
Busanan Ongbamrungphan, another Thai hope in the women's singles, also lost her opening match, falling to China's Wang Zhiyi 19-21, 14-21 in a Group A clash.
Busanan will face Gregoria Mariska Tunjung of Indonesia in her second match on Thursday.
Tunjung also lost her opening match to Aya Ohori of Japan 15-21, 13-21.