World number one Lydia Ko fired a bogey-free four-under-par 68 to sit three shots off the lead after the first round of the LPGA Thailand on Thursday.

Japan's Nasa Hataoka, China's Lin Xiyu and Anna Nordqvist from Sweden were among five players at the top of the leaderboard at Siam Country Club Pattaya.

American Jennifer Kupcho and local hope Jaravee Boonchant -- a rookie ranked 238 in the world -- were the other two.

New Zealander Ko came into the 1.7-million-dollar event in ominous form.

The Seoul-born 25-year-old has won three events in her last four starts. She is also newly married.

Ko, who carded four birdies, was in a share of 17th alongside South Korea's former world number one Ko Jin-young and current world number two Nelly Korda.

Also in 17th after a blemish-free 68 was last year's winner Moriya Jutanugarn, the first Thai to claim victory in the tournament.

She was thrilled to be playing in front of an enthusiastic home crowd after the Covid pandemic.

"We don't have that (many fans) like really the last two years, and this is the first time since we came back like fully 100 per cent," she said.

Kupcho carded five birdies and an eagle for her opening 65 and a share of the lead.

She said she felt very much at home, having finished in a tie for sixth at the same event in Thailand last year.

"I think I'm really comfortable with this place. I played really well last year," the 25-year-old American said.

American Lilia Vu, Maja Stark from Sweden and South Korea's Jenny Shin were all one shot off the lead.