GREATER NOIDA, India, March 14, 2013 (AFP) - Eight of Chinnarat's 11 birdies on the Greg Norman-designed par-72 Jaypee Greens course outside New Delhi came on the inward half -- his 61 leaving him well ahead of the chasing pack in the $2.3 million tournament.
"This has to be the best round of golf I have ever played," the 24-year-old winner of three Asian Tour titles said. "It was just so smooth for me out there.
"My previous best was nine-under, but this round has also put a bit of pressure on me to do well over the next three days. I hope I can be relaxed."
Chinnarat's sublime putting -- including a 50-foot putt on the 14th -- left him five clear of compatriots Chawalit Plaphol and Chapchai Nirat, China's Liang Wenchong, Swede Magnus Carlsson and local player Abhijit Singh Chadha.
Eight players were tied in third place at five-under while 15 others were one shot back in a low-scoring start to India's richest golf event co-sanctioned by the European and Asian Tours.
However, it was a miserable opening round for Ryder Cup great Colin Montgomerie who shot a four-over par 76, leaving him with a tough battle to make the cut.
Chadha, a 21-year-old playing for the first time in an European Tour event, gave the home fans something to cheer about with his six-under-par score.
"I've got no experience at all," the Indian Tour regular, who only turned professional last year, said.
"Playing with the big boys really gives you lots of confidence and it's a really good feeling for me."
Spaniard Alvaro Quiros, Thongchai Jaidee of Thailand and Simon Khan of England finished at two-under 70, while Edoardo Molinari of Italy came in with a level-par 72.
Leading scores after the opening round in the $2.3 million Avantha Masters golf at the Jaypee Greens in Greater Noida on Thursday (par 72):
61 - Chinnarat Phadungsil (THA)
66 - Abhijit Chadha (IND), Chawalit Plaphol (THA), Magnus Carlsson (SWE), Chapchai Nirat (THA), Liang Wenchong (CHN)
67 - Joonas Granberg (FIN), Jaakko Makitalo (FIN), Thomas Aiken (RSA), David Drysdale (SCO), Rikard Karlberg (SWE), Scott Hend (AUS), Scott Barr (AUS), Rashid Khan (IND)
68 - Kiradech Aphibarnrat (THA), SSP Chowrasia (IND), Anirban Lahiri (IND), David Howell (ENG), Gaganjeet Bhullar (IND), Emilliano Grillo (ARG), Pablo Larrazabal (ESP), Peter Whiteford (SCO), Prom Meesawat (THA), Robert Coles (ENG), Brett Rumford (AUS), Mardan Mamat (SIN), Ashok Kumar (IND), Maximilian Kieffer (GER), Baek Seuk-Hyun (KOR)
69 - Niclas Fasth (SWE), Oliver Fisher (ENG), Raphael Jacquelin (FRA), Julien Quesne (FRA), Berry Henson (USA), Tommy Fleetwood (ENG), Kim Chan (USA), Matthew Baldwin (ENG), Darren Beck (AUS), Rahil Gangjee (IND), Kristoffer Broberg (SWE), Ricardo Gonzalez (ARG), Jeev Milkha Singh (IND), Victor Dubuisson (FRA), Bjorn Akesson (SWE)
Selected scores:
70 - Alvaro Quiros (ESP), Thongchai Jaidee (THA), Simon Khan (ENG)
72 - Edoardo Molinari (ITA)
76 - Colin Montgomerie (SCO)