Atthaya Thitikul moved to the top of the leaderboard after a second-round 64 at the Dutch Junior Open at Toxandria Golf Club in Breda.
The 14-year-old Thai amateur became the youngest known winner of a professional golf tour event with a victory at the inaugural Ladies European Thailand Championship in Pattaya earlier this month.
Atthaya fired 11 birdies against three bogeys on Thursday. She was on nine-under 135, five shots ahead of China's Liu Yiyi, who shot a 69.
Fellow Thai Manuschaya Zeemakorn was two-over after a 74.
In the boys' event, Sadom Kaewkanjana shot a 68 to end the second day on four-under 140, five shots behind leader Thomas Sloman of England who added a 68 to his opening 67.
Another Thai Atiruj Winaicharoenchai (68) was tied for 11th on one-under 143.
In Hua Hin, Jazz Janewattananond and Gunn Chanroenkul shared the clubhouse lead at the rain-hit Singha Hua Hin Open yesterday.
Jazz shot a second-round 68 while Gunn fired a 66 to move to nine-under 133 at Royal Hua Hin Golf Course.
A total of 17 players return to the course at 6.50am this morning to complete their second round, with the third round starting at 9.30am.