The Thais produced a classy performance at the Royal Mingalardon Golf and Country Club as they lead by one-shot over countryman Prom Meesawat, who is searching for a long-awaited second Asian Tour victory and Joonas Granberg of Finland.
Thanyakon Khrongpha cemented the Thai presence by sharing fifth place with Australia's Darren Beck and Koreans' Hwang In-choon and Young Nam and at the US$300,000 event which is the curtain raiser for the 10th Asian Tour season.
Reigning Asian Tour number one Thaworn Wiratchant of Thailand, who had the honour to hit the first drive to commemorate the occasion, settled for 71 together with title holder Kieran Pratt of Australia.
The big-hitting Kiradech was six-under through eight holes but his confidence took a dent when he missed a 10-foot birdie putt on the 10th hole. He gradually recovered and took advantage of the par fives where he birdied 14 and 18.
"I missed a big putt on the 10th hole. I had a 10 feet uphill straight putt but I pulled it. After that I lost some confidence with the putter. I was lucky get to get two birdies in the next par fives," said the 23-year-old, who is hunting for a second Asian Tour victory.
Last year's play-off defeat was agonising for Kiradech but the man nicknamed 'Asia's John Daly' for his rip-it and grip-it style of play, believes he has grown into a better player.
"I always try to get better and better. I lost in a play-off last year and I even lost in the pro-am on countback this week (to Pratt)! But my game is better than last year. This year I'm hitting it better," smiled Kiradech.
The tenacious Chapchai was even-par after five holes but recovered with eight birdies in his last 13 holes to share the lead. He holds the world 72-hole scoring record with a stunning 32-under-par 256 winning total in India in 2009 but has yet to win since then.
"My putting was very good. Last year I struggled with my putter. Usually when you start the first tournament, you feel a bit uneasy but it was different today. Putting is very important for me. If I can putt well, I will feel confident," said Chapchai, who welcomed his new born son 'Jedi' to his family last year.
Granberg, who is among three Finnish players this week, shot his best round since winning his first Asian Tour title in 2011 and will take pride in his return to form after a dismal 2012 season.
"This is a very low score already and I just wanted to play and relax. There was nothing special in my round. I hit it very good off the tees and found about 13 fairways. It was solid golf. I struggled last year. I had some personal problems and was dealing with that. I'm feeling better now," said Granberg, who carded five birdies and one eagle.
Playing on minimal Asian Tour events in the last three years, Nam rediscovered his love for golf at the right time and was tied for the lead before dropping shots in his last two holes.
"Golf wasn't really on my mind in the last three years or so. I'm here to enjoy the game now. I'm not getting any younger. There's pressure out there but less pressure. Playing with a free mind has made golf a little bit easier for me," said the 39-year-old.