The Thai, three-times Asian champion, played just one hole of his first round on Thursday when fog stopped played for more than six hours at the $2.9 million European and Asian Tour event.
An early starter on Friday, he completed an opening three-under-par 69 before heading out again to go two shots better in his second round, enough to land him at eight-under-par alongside Argentine Tano Goya at the Pinx Golf Club.
"I played a total of 35 holes today and it was really a long and tiring day," Thongchai said.
"But I'm really happy that I was able to play really well throughout the day." Goya, a European Tour winner at the Madeira Islands Open last year, played 34 holes for a 66 and 70 to join Thongchai in the three-stroke clubhouse lead over Dutchman Robert-Jan Derksen and Swede Johan Edfors.
"I focused on trying to play hole by hole, shot by shot, and trying not to complain," said Goya. "I just had to focus."
First-round leader Marcus Fraser, who shot an opening 65, three-times major winner Ernie Els and American Anthony Kim, who both had 68s to stay in contention, will not start their second rounds until Saturday.
US PGA Championship winner Yang Yong-eun, Asia's first major winner and champion at the China Open last week, had a disappointing day on his home Jeju island and faces missing the cut after completing rounds of 77 and 73.
Despite an early morning start on Friday to try and clear the backlog, and bearing in mind the flight problems for players heading back to Europe, tournament directors decided to reduce the event to 54 holes and ensure a Sunday finish.
"After reviewing the amount of golf completed yesterday, it has become clear that the completion of 72 holes within the required time frame is not feasible," they said in a statement.
The cut will be made after the second round is completed on Saturday with the top 65 and ties going through to a final round shootout on Sunday.
