Singapore - Former world number one Lydia Ko laboured to joint 27th place with a one-under 71 after the first round of the HSBC Women's World Championship in Singapore on Thursday as the world's top players struggled to find control under Singapore's signature sultry conditions. 

Unheralded American Jennifer Song took the lead with a seven-under par 65 at the end of day one with China's world number one Feng Shanshan left five strokes behind on two-under par. 

American world number two Lexi Thompson never got hot on her way to a three-over 75 as the heavens threatened to open and then caused a more than two-hour break in play with the last three groups still out on the course. 

Song twiddled her thumbs in the clubhouse then finished off a day where there were no blotches and seven birdies on the 66th-ranked player's card at the death as she chased her first-ever win on the LPGA Tour. 

"I'm not really thinking about winning or anything," said Song. "I just want to take it day by day. 

"There's a lot of great players out here, so it's a golf course where a lot of players can shoot low numbers. So I just need to keep grinding and do the same thing." 

Looming with intent was American Michelle Wie, once arguably the most famous female player on the planet after turning pro aged 15 back in 2005 - a move unheard of at the time. 

The now 28-year-old shot a first-round five-under 67 to sit tied for second with South Korea's Ji Eun-hee. 

She took time to reflect on the flood of teenagers now involved in the game at the very top level, including 15-year-old Thai amateur sensation Atthaya Thitikul, who is also competing at the Sentosa Golf Club. 

"They are doe-eyed and so full of hope in their eyes, everything is great. I'm like: You. Just. Wait. A couple years," laughed Wie, who came under intense media and public pressure in her early years on Tour. 

"But you know, it's great," Wie continued. "It's actually refreshing to see them full of just 'everything is new', and everything is untarnished. It's actually fun to watch that." 

The last event the American won was the 2014 US Open but there have been plenty of near misses in the years since, including a tied-third at last year's British Open. 

A bogey on the last - when she shot a 40-foot birdie putt way wide to the right - took the sheen off an otherwise tidy day at the office and Wie said she had learnt, over the years, how to better live with life's disappointments. 

"I think I do a lot less now," she said. "I just chill. I'm just really tired all the time, so I just sleep and I just eat and I just watch a lot of Netflix. I'm really into Riverdale right now. Not too proud of it but it's really good." 

This year's Women's World Championship has attracted 19 of the world's top-20 players but any worries that Thitikul might be overawed were blown away when the young Thai - who won last week's Women's Amateur Asia-Pacific championship to qualify for the event - saved her round with four birdies before signing for a two-under 70. 

In fact pressure so far seems to have had little effect on the star who last year became the youngest known winner of a professional golf tournament with a two-shot victory at the Ladies European Thailand Championship in Pattaya - aged just 14 years and four months. 

Thitikul said after her first round that her pre-event game plan had been to go out there and enjoy herself. 

"I just want to have fun," she said. "I sing a little bit, a Thai song that's funny and helps me calm down when I have a bogey."