Chapchai was one of 78 players, including world number one Rory McIlroy, stranded on the course on a storm-threatened Thursday but he returned early on Friday to complete a bogey-free six-under 65 for a one-shot lead after the first round.
Resuming on three-under after five holes, the stocky 29-year-old added three birdies, including one at the par-five 18th, to move a stroke clear of overnight leader Thomas Bjorn of Denmark before rushing off to start his second round.
The Thai cancelled out two birdies with as many bogeys in the nine further holes he completed before a tropical downpour brought an early conclusion to the day without a single player in the 150-strong field having completed 36 holes.
Chapchai was joined by Simon Dyson at the top of the leaderboard after the Briton recorded four birdies in a blemish-free 13 holes. Dyson will drop at least one shot on resumption after a par putt on his 14th hole shaved the cup shortly before the suspension.
McIlroy was even par when he resumed on the ninth hole in the morning and the Northern Irishman was steady for the remainder of his round, birdying the par-four 11th and parring the other holes to register a one-under 70.
However, the world number one looked in danger of missing the cut after dropping three shots early in his second round but he steadied the ship and recorded three birdies in four holes to move back under par for the tournament after 30 holes.
Italian duo Matteo Manassero and Francesco Molinari moved confidently up the leaderboard to lurk one off the lead with a few holes to play in their second rounds, level with Bjorn, who has only completed 18 holes and did not hit a single shot on Friday.
Chapchai often struggled to contain his temper when things were going wrong on the course but the practicing Buddhist explained that regular meditation had helped soothe his nerves.
"Yes, I've been going (to the monastery) a lot to calm myself out," Chapchai said.
"I used to be very hot-tempered and I would get frustrated easily, especially when I was younger.
"My parents sent me to the monastery and I became a monk for a while. My temper is better now but I still try to go back to the monastery once in a while."
Looking to end a victory drought dating back to March 2009, Chapchai believes ironing out problems with his putter will be key to his performance in the event.
"I've been having problems with my putting for the whole of this year," he added. "I try to make sure that I've got enough practice before coming to play here. It seems to be working out today. I was hoping to solve the problem this week.
McIlroy, watched this week by tennis-playing girlfriend Caroline Wozniacki, admitted the break in play had not hampered his concentration but he was a little disappointed with his display on the greens.
"With the weather we have here at this time of the year, you have to expect some disruptions," he said.
"I actually played pretty well from tee to green, just didn't really hole any putts, which was a bit frustrating. So that was the story of the round really."
Juvic Pagunsan, who lost in a playoff to Gonzalo Fernandez-Castano a year ago, became the second player this week to record a hole-in-one when the Filipino aced the par-three second. Italy's Edoardo Molinari aced the par-three 17th on Thursday.
Play will resume at 7.30am on Saturday (11.30pm Friday UK time) with more than half the field yet to start their second rounds.
Tournament director Jose Maria Zamora released a statement in which the organisers were aiming to complete a full 72-hole event but the draw for the third round, after the cut, would remain the same for the final round to save time.
"However, if we do suffer more delays we would then decide, in consultation with the sponsor and promoter, whether to reduce the tournament to 54 holes or complete the fourth round on Monday," the statement continued.
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