Thailand's Prayad Marksaeng maintained his title charge at the inaugural Chiangmai Golf Classic presented by PTT with a second round of five-under-par 67 to stretch his advantage to two shots on Friday.
The overnight leader, who is a six-time Asian Tour winner but has not on the region's premier tour since 2007, tightened his grip atop the leaderboard with his 12-under-par 132 total at the Alpine Golf Resort-Chiangmai.
Thongchai, who needs a win in Chiangmai to qualify for the Masters Tournament, shot a fabulous 65 to move to tied second place with American Jonathan Moore (68) and India's Digvijay Singh, who birdied his last three holes for a 67.
The powerful Yang shot a 68 and will enter the weekend rounds four back while Ernie Els of South Africa, using a short putter for the first time in a long while, battled to a 71 for tied 41st place on 140.
Prayad, who stuck to the cross-handed putting grip which he changed midway through the first round, credited his fine form to his new irons and golf ball.
"I changed to a new golf ball and it seems to be giving me more distance. Last time I hit my driver to about 280 yards but now I'm hitting it 20 yards longer. I'm getting more distance and that's good for my age," said the 47-year-old Prayad.
Starting from the back nine, Prayad, who has won three titles on home soil this year including his national Open two weeks ago, bounced back from an early bogey on two with acurate irons shots and was rewarded with six birdies, which all came inside of 10 feet.
"I'm happy with how I played. My game, from my driver, irons and putting, were very good. I used the cross-handed grip again today. It seems to be working. I've been playing very good this year and I hope I can maintain my form," added the smiling Thai.
Three-time Asian Tour number one Thongchai produced some wonderful golf to put himself in position to win and break into the world's top-50, which is required to earn an invitation to the Masters Tournament next month.
The former paratrooper birdied the third from close range and then holed out with a wedge for a stunning eagle three on the fourth hole which sparked his round. He added four more birdies on the back nine as he outshone playing partner Els.
"It is actually a good idea to keep thinking about the Masters Tournament," said Thongchai, who is ranked 59th in the world. "
"I want to win this tournament. It is only the second round and I'm halfway there. I think I have a good chance because I'm only two shots away. If I can get another low round then I have a chance of winning," add the Thai, who has 13 titles on the Asian Tour, which is celebrating its milestone 10th season in 2013.
"A few things I've learned over the years, one of them is to send the ball on its way. I can't make it go to a particular spot. Just envision that all I'm going to do is to hit it into the ocean instead of a small fairway. Just make that free swing and hit it into a big wide ocean. I think that's helped a bit," said Moore, who hit 10 fairways and 14 greens in regulation.
Singh was delighted to be feature on the leaderboard again, nearly a year after he claimed his breakthrough victory at the Panasonic Open India which he will defend the title next week.
The halfway cut was set at two-under-par 142 with a total of 71 players making the weekend rounds.