BANGKOK: World number one Akane Yamaguchi suffered a second defeat in three days at the Thomas and Uber Cup Finals in Thailand on Friday as Japan were dumped out in the semi-finals by South Korea.
An Se-young's battling win over Yamaguchi set the Koreans on their way to a 3-0 victory and a place in Saturday's final of the women's team championships against China.
Holders China defeated hosts Thailand by the same 3-0 scoreline in Bangkok in the other semi-final.
Cheered on by her Japanese teammates whacking drums and shaking tambourines, world champion Yamaguchi dominated the first game 21-15 against the world number four An.
She also looked in control early in the second game, but the 20-year-old An was able to turn around a six-point deficit.
A spate of unforced errors from Yamaguchi also contributed to An's change of fortune as she won the second game 21-18.
Yamaguchi carved out a five-point lead in the deciding game but a seven-point run from An saw Yamaguchi's frustrations grow.
An epic 44-shot rally took its toll on the Japanese as An levelled the scores at 18-18.
Two critical errors from Yamaguchi saw the youngster gain the upper hand and then seal the match 21-18, before lying on the floor screaming in delight.
"During the game I tried to increase the speed of the shuttle but... I would lose control, it caused many mistakes," Yamaguchi told reporters.
On Wednesday, Yamaguchi suffered a shock loss to Bilqis Prasista, a teenage Indonesian rookie ranked 333rd in the world.