But it was not the same for Australia's Hannah Green, who will be hoping her late stumble won't prove too costly come the end of the tournament.
Jennifer Kupcho shot 69 in the morning, finishing with a 15-foot par save on the par-4 18th that was playing more than one shot over par for the early starters. The greens were firm and the rough was thick, putting a premium on par.
Thitikul experienced that when she didn't make a birdie until her eighth hole, the par-5 17th. But then Mountain Ridge got just enough rain to take some of the fire out of the course, and the wind seemed to leave town with the light rain.
"Luckily we don't have much wind on the back nine after the rain came, and then the wind just like shut down," Thitikul said. "Then we just lucky. If we got the breeze (like on) the front nine, I don't think my number is going to be that low, for sure."
The world No.2 is at eight-under 136 going into the weekend with a chance to win for the first time this year, and the first time since losing her No.1 ranking to Nelly Korda, who is not playing this week.
Conditions were so tough late in the morning Lydia Ko had an easy time accepting her 75, that ultimately put her six shots out of the lead.
"Probably one of the rare occasions where you shoot 75 and you're not like stressing out too much about it," Ko said. "The greens are pretty undulating and you leave yourself in some positions above the hole and you don't even know if you can hold it on the green at that point."
World No.5 Green has been in sublime form this season with two wins - the HSBC Women's World Championship and Los Angeles Championship - and two top-10 finishes in her last five starts.
The Western Australian posted a one-over 73 after making two bogeys in her closing four holes to drop six strokes behind Thitikul.
Green, who is tied fifth, had bogeys on the third and fifth before making birdies on the eighth and 13th to even her card.
Then came her lapses on the 15th and 18th, that were sandwiched by a birdie on 17.
Cassie Porter (72) and Robyn Choi (73) are tied 15th and the next best Australians at even par.
Brooke Matthews had a 72 and was four shots behind, while Celine Boutier of France shot 68 and was five back at three-under 141.
with AAP
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