Tournament host K.J Choi of Korea trailed closely behind Chinnarat after reaching the turn at 11-under-par to stay one shot back of the Thai while Korea's Kim Dae-hyun believes that staying patient would be key after he took third place at 10-under-par through 10 holes.
With almost four hours of play lost due to heavy fog in the morning, 62 players will have to return on Sunday morning to complete their third round at 9.20am with the final round scheduled to start at 10.20am.
Playing alongside tournament heavyweights, Choi and American Ben Curtis, Chinnarat held his own when he got off to a par-birdie-birdie start at the Haesley Nine Bridges Golf Club.
The 23-year-old parred the rest of the holes but had a nasty scare on the par-three eighth when his wayward drive found the greenside bunker.
He recovered well with an impressive up and down before saving par with a 10-feet putt at the US$750,000 event which is jointly sanctioned by the Asian Tour and Korean Golf Tour.
"K.J. is a very good player and he knows how to win tournaments. So it's not over yet. But today [Saturday], the most important thing was that I was very relaxed. I was not nervous and I just played my own game," said Chinnarat.
Chinnarat, who became the youngest winner on Tour when he won his first title on home soil at the age of 17 years and five days, is hopeful that his solid run will continue as he is beginning to rediscover his winning form that led him to three Asian Tour titles.
"I'm beginning to play well now and I feel confident. I'm going to try my best tomorrow [Sunday] and hopefully I'll win," said Chinnarat, who has enjoyed two top-10 finishes on the Asian Tour this season.
Choi, who resumed his second round only to card two bogeys in his remaining four holes earlier in the day, put up a better performance in the third round when he charged back into contention with a flawless outward-nine that was highlighted by three birdies on the second, eight and nine holes.
"I didn't really get back into the rhythm in the morning but it's okay, I made it up with in the afternoon," said the Asian Tour honorary member.
Meanwhile Kim is planning to adopt a conservative approach when he returns to complete 26 holes on Sunday.
"There're still many holes to play tomorrow [Sunday] and it would not be wise to play aggressively. I prefer to stay patient and attack the pins when I've the chance," said the 32-year-old, who topped the KGT Order of Merit in 2010.