Overnight leaders Nattawat Suvajanakorn and Supamas Sangchan dropped back after the second round of the 79th Singha Thailand Amateur Open yesterday.
Nattawat shot a second-round 71 with four birdies against three bogeys for a five-under-par 139 in the men's event.
The Thai national player was tied for second with Singapore's Jorome Ng (68). They were two shots behind Jorda Surya Irawan of Indonesia, who posted a 68 for a seven-under-par 137 at Panya Indra Golf Club.
The 17-year-old Irawan is hoping to win the title to boost his confidence before participating in the SEA Games in Myanmar in December.
Poom Saksansin (69) and defending champion Itthipat Buranatanyarat (71) were at 141 and 142 respectively.
Struggling with an opening 75, Danthai Boonma reeled off three birdies in his bogey-free round for a 144.
In the women's event, Princess Superal, 16, of the Philippines fired a second-round 70 with three birdies against one bogey to take a two-shot lead on 142.
Local hope Parinda Phokan stayed second on 144 following her 71 while overnight leader Supamas shared third place on 145.
Supamas, who will represent Thailand at the SEA Games, yesterday failed to get a single birdie and suffered a double bogey and a bogey.
The Thailand Amateur Open tournament, the oldest golf event in the country, attracts more than 125 players from 16 countries this year.
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