Ai Miyazato shot a 5-under 67 Thursday to take a one-stroke lead after the first round of the LPGA Thailand.
The 2010 champion from Japan opened with a birdie and had four more on a warm and humid day at the Old Course at Siam Country Club.
American Paula Creamer had a hole-in-one on the 146-yard 12th hole, hitting a 7-iron that one-hopped into the cup. She's five shots behind the leader.
"It was a really, really long day for me because of the temperature," said Miyazato, who was playing in her first LPGA event of the year. "I felt really calm this morning, so I could control myself really well out there. So that's why I think I had five birdies and no bogeys today. Overall, I hit the ball well and my putting was really good. I had a few really good up and downs."
Third-ranked Na Yeon Choi, Se Ri Pak, Amy Yang, Anna Nordqvist and Karrie Webb were one shot behind.
Numa Kulyanamitta (69) was tied for seventh along with Christel Boeljon, while Stacy Lewis (70) dropped off the top of the leaderboard with a triple-bogey on the last hole.
The fifth-ranked Creamer has been working on changes to her swing and the ace helped her salvage a 72 that was good for a tie for 26th.
"I'm still trying to find a bit of my rhythm," Creamer said. "I feel good to have my first round under my belt. I'm really working hard on my golf swing, so I'm probably the most technical that I've ever been. That's something I have to get used to and just being out there in competition."
Webb also made changes to her swing and felt good about the adjustments after four birdies on the back nine.
"A little scratchy on the front nine, but I sort of managed it," she said. "I didn't miss too many greens and I made some good two putts from long range. But on the back nine, I started to hit my irons better and gave myself quite a few birdie chances."