BANGKOK, Nov 29, 2012 (AFP) - Mardan, who stormed home with five birdies on the closing five holes, leads Supakorn Utaipat of Thailand and England's Chris Rodgers by one stroke at the Singha Park Khon Kaen Golf Club in northeastern Thailand.
The 45-year-old's only blemish came with a par-three bogey on the 13th before he hit the birdie trail again.
"It has been some time since I shot nine-under and obviously it's a very good score that I can be very proud of," said Mardan, who has won three times on the Asian Tour.
"I holed many putts and that was basically the key to such a good round today."
Supakorn, 22, who only turned professional this year, was delighted with his encouraging start to the tournament.
The $500,000 King's Cup is making its return after a year's absence following floods in Thailand last year.
Australia's Rick Kulacz signed for a 65 to take equal fourth place alongside Spain's Javi Colomo and Thai trio Arnond Vongvanij, Prom Meesawat and Udorn Duangdecha, who won in 2010.
Thailand's Thaworn Wiratchant, currently second in the Asian Tour Order of Merit, is six shots off the pace.
Leading scores after the first round of the King's Cup (par 72)
63 - Mardan Mamat (SIN)
64 - Supakorn Utaipat (THA), Chris Rodgers (ENG)
65 - Rick Kulacz (AUS), Udorn Duangdecha (THA), Arnond Vongvanij (THA), Prom Meesawat (THA), Javi Colomo (ESP)
66 - Felipe Aguilar (CHI), Lin Wen-tang (TPE), Pariya Junhasavasdikul (THA), Wittawat Sae-Ung (THA)