Sudaporn Seesondee edged Great Britain's Caroline Dubois 3-2 in the women's boxing lightweight (60kg) quarter-finals at the Tokyo Games on Tuesday.
The Thai boxer won the first round but Dubois came back to superslot even the match in the second round. The Udon Thani native powered past her opponent in the deciding bout to close the contest 3-2 in a nail-biting match.
The win guaranteed her at least a bronze medal. She will be the first female Thai boxer to get an Olympic medal. Her march to a semi-final spot will earn her a position as a civil servant in the Royal Thai Navy.
She will meet Kellie Harrington from Ireland in the semi-finals.
Sudaporn, a silver medallist at the 2018 world championships, comfortably beat Simranjit Kaur of India 5-0 in the round of 16.
The Thai team has so far won only one medal. Taekwondo champion Panipak Wongpattanakit took gold in the women's 49kg event.
Meanwhile, Sudaporn said she felt the pressure before competing. But she told herself not to let it get the better of her during the match. She had also studied the boxing style of her opponent, which worked to her advantage.
After winning, she was overjoyed and speechless. Sudaporn said she owed her victory to her late father, Yodnakhon Seesondee, who taught her not to give up on boxing.
"I just want him to know I've done it. I've done you proud," she said.
On Tuesday, navy commander Adm Chartchai Sriworakhan said he phoned Sudaporn, who is also a volunteer ranger, to congratulate the boxer on her victory.
The commander commended her for her dedication despite the difficulties in training posed by Covid-19 restrictions. Adm Chartchai said Sudaporn was one of the country's sporting ambassadors and stressed the importance of upholding the spirit of sportsmanship.
Sudaporn graduated with a degree in education from the Institute of Physical Education's Sukhothai campus.