The overnight co-leader, Yamashita posted three birdies on the back nine, where she started, but she struggled on the front to close with a nine-under-par 135 at the par-72, 6,550-yard Blue Canyon Country Club.
“My shots weren’t as accurate today, and I didn’t get as many chances as I wanted. I feel like I could have pushed my score a bit more,” said the 13-time JLPGA Tour winner. “I want to achieve my target score, so I’ll focus on improving over the next two days. My goal is to win, so I’m putting everything into every shot.”
KLPGA Tour No. 7 Yoo remained bogey-free with a 67 to join the leading pack.
“There were quite a few crisis moments during today’s game, but I managed to overcome them well,” said the 20-year-old, a one-time KLPGA winner. “Despite the challenges, I was able to maintain a good flow, make a lot of birdies, and avoid mistakes.”
China’s Li, 21, fired the round’s lowest score with a superb 65, highlighted by four birdies on the front nine and three more on the back. The in-form Chinese player recently finished tied for fifth at last week’s LPGA event in China.
Among the Thai contenders, former Thai LPGA Order of Merit winner Arpichaya Yubol battled through a wrist injury to shoot 71, placing her at six-under 138, the best score among local competitors.
“Every time I play at home, I feel the pressure to perform well,” said Arpichaya. “I end up trying too hard and pushing myself too much. On top of that, my left wrist is painful. I’ll need a full month off to rest and recover.”
The championship continues over the weekend, with the trio of leaders poised for a thrilling contest in the final two rounds.