David Micheluzzi was the leading Australian after the opening round of the Singapore Classic, his five-under 67 giving him a place in the top-10, three shots off the lead.

The 27-year-old Melburnian, who was order of merit champion for the PGA Tour of Australasia last year, birdied the last three holes at the Laguna National Golf Resort Club on Thursday.

It left him in joint-ninth position after the first round, with Gavin Green, Kiradech Aphibarnrat and Jordan Smith sharing the lead following eight-under 64s.

Green, from over the border in Malaysia, holed a 40-footer for eagle at the third hole and birdied seven of his last 12 holes late in the day to join Thailand's Aphibarnrat and England's Smith in a tie for first.

Smith, the world No.88 and coming off a second-place finish at the Jonsson Workwear Open two weeks ago, was bogey-free and finished with an eagle at the par-five last.

The world No.441 Aphibarnrat, who had nine birdies, is looking to win for a fifth European tour title and for the first time since 2018.

They were a stroke ahead of Ugo Coussard, of France, and two clear of Andrea Pavon, Grant Forrest, Richard Mansell and Freddy Schott.

Shane Lowry flew in from The Players Championship on the PGA Tour, where he was tied for 19th on Sunday, and shot three-under par after just one practice round. The 34th-ranked Irishman made three birdies in his first four holes and then two more in his final four holes, but none in between.

"I felt like golf was easy and that everything was going to be easy today," Lowry said of his strong start.

"But it bit me back. I need to be a bit more in control of my emotions tomorrow and play it one hole at a time."

The other two Australians to make an under-par start were Deyen Lawson (70) and John Lyras (71).

Tom Power Horan went round in 73, one ahead of fellow Aussies Andrew Martin and Jason Scrivener.