Former world No. 1s Tseng Ya-ni and Park In Bee fired matching six-under 66s on Thursday to share the opening-round lead at the HSBC Women's Champions.

They are a stroke ahead of 2012 winner Angela Stanford, with a clutch of five players including current top-ranked Lydia Ko, a further shot adrift at the US$1.4 million (S$1.9 million) tournament.

Park, the world No. 2 after being overtaken by Ko last month, was thrilled with her hot start at the Sentosa Golf Club's Serapong Course.

She said: "Today was a really good day. I had a bogey-free round, especially on this golf course which is a very challenging and I'm really proud of that."

After opening with eight straight pars, the 26-year-old from South Korea got going with her putter as she holed six birdies in the next 10 holes, including on 17th and 18th.

She said: "These are big greens and you have to pace yourself really well on the greens. They are very grainy greens, and I hit a lot of shots close today.

"I think today's pins are one of the easiest pins we're going to get all week, so it's good that I took advantage of that."

Sharing her sentiment was Stanford, who also did not drop a shot and fired five birdies.

Said the 37-year-old American: "The pin positions were very friendly out there today. I'm sure it's going to get tougher from tomorrow."

Despite two bogeys on her scorecard, Ko, 17, was pleased with her effort and her ability to cope with the sapping tropical heat.

Said the South Korean-born Kiwi, who arrived on Monday from Christchurch: "We were a bit spoilt with the fantastic weather last week. The heat is really going to be the biggest obstacle for me out here. But I gave myself many birdies opportunities and I felt good with my putter."

American defending champion Paula Creamer, one of the biggest names in the elite 63-woman field, opened with a 74 and is tied for 51st.

Singapore's Koh Sock Hwee, the only amateur in the field, was last after signing for a 79.