China's Guan Tianlang, who turned 14 last week, collected nine birdies en route to an eight-under-par 64 to stretch his lead to five strokes at the halfway stage of the Asia-Pacific Amateur Championship in Bangkok.
The winner of the tournament earns a spot in the 2013 Masters and into international final qualifying for the Open Championship at Muirfield. The runner-up also is exempt into final qualifying for the Open.
Thai Prin Sirisommai led the local charge by moving to nine-under following a 65, after setting a championship nine-hole record with a 29. Australian Oliver Goss, a U.S. Amateur quarterfinalist, later carded a bogey-free 65 to share the second spot at Amata Spring Country Club in Chonburi.
Top Thai amateur Natipong Srithong, winner of last year's Southeast Asia Games, was three shots back after a second 69.
Nathan Holman of Australia shot a 64 to share fifth at five-under with Lee Soo-min of Korea, last year's runner-up, who carded a 70. Hideki Matsuyama, who has made the cut in the past two Masters, continued his bid for a third straight title with a 69 that left the Japanese star 4-under and 10 strokes off the lead.
Guan, the first-round leader with a 66, moved to 14-under after the second day of play. Starting on the back nine, he birdied his first two holes before picking up further shots on 15 and 17. On the front nine, he hit three straight birdies, including a chip-in on the third, and he added two more birdies at six and seven, the latter with his second chip-in of the day.
However, on his last hole, the 464-yard par-four ninth, Guan hooked his three-wood approach, chipped to eight feet and lipped out with his first putt for his only bogey in a sensational round.
"My feeling with the putter is fantastic and that's why I've got a low score. I think I had 25 putts yesterday and maybe it was a little lower today, perhaps 22, as I had two chip-ins," said Guan, who won by 11 shots in his age division (11-12) last summer at the junior world golf championships in San Diego.
"I had two birdies in the first two holes and felt very comfortable after that. I just kept going and I'm happy I only made one bogey," said Guan, who was the youngest-ever winner of the China Amateur Open last November.
Goss, a Perth-based 18-year-old who heads to the University of Tennessee next year, joined the front of the chasing pack with a flawless round that included an eagle at the par-five second, where he sank an 80-foot putt from a few feet off the green.
The tournament is run by the Asia Pacific Golf Confederation, along with the Masters tournament and the R&A.
Information from The Associated Press was used in this report.