HOUSTON, United States (AFP) — Thailand’s Jeeno Thitikul fired a four-under-par 68 to edge into a slender lead as searing heat and humidity tested players in the opening round of the KPMG US Women’s PGA Championship in Texas on Thursday.

The 22-year-old, who is chasing her first major victory after seven top-10 finishes, reeled off six birdies to move into a one-shot lead.

Meanwhile, Filipina golf star Bianca Pagdanganan carded a two-over-par 74 at the demanding Fields Ranch East course in Frisco, Texas.

Starting on the back nine, Pagdanganan got off to a promising start with a birdie on the par-5 10th, but stumbled with bogeys on the 16th and 17th. The front nine proved just as challenging, as she dropped two more shots on the 5th and 7th holes.

Despite the setbacks, the 26-year-old showed flashes of her trademark power and precision. Pagdanganan hit 13 of 18 greens in regulation and found 10 of 14 fairways, averaging a booming 267 yards off the tee — among the longest hitters in the field. Her putter, however, was tested throughout the round as she needed 31 strokes on the greens to complete the day.

It was a steady, if slightly frustrating, start for Pagdanganan, who is seeking a breakthrough performance in what is the LPGA Tour’s third major of the season.

With three rounds to play, the Filipina is determined to find her rhythm and climb the leaderboard heading into the weekend.

Jeeno’s only blemish on an otherwise flawless opening round was a double-bogey six at the par-four fourth hole of PGA Frisco’s 6,404-yard layout.

The rising Thai star, who has already amassed 18 wins as a professional including five on the LPGA Tour, said she had taken a patient approach after shrugging off her early double-bogey disappointment.

“I think like all the majors, I have told myself just to be really patient,” Jeeno said after her round. “I definitely know that I’m going to miss a shot or make a bogey during the day.

“Don’t be like, moody... I told myself be patient and focused on the next shot.”

Jeeno was one shot clear of Australia’s Minjee Lee, who had a roller coaster round that included seven birdies and four bogeys en route to a three-under-par 69.

Lee was satisfied with her round but admitted the searing temperatures in the high 90s (Fahrenheit) were challenging.

“I just kept telling my caddie, can you give me another water, can you give me another water,” Lee said. “I don’t think we could have enough (water) out there. It’s really hot.”

Japan’s Rio Takeda, South Korea’s Lee So-mi and American Yealimi Noh were a further shot back after carding two-under-par 70s.

World number one Nelly Korda, meanwhile, is four off the pace after an opening level-par 72.

Korda also admitted she had found the heat a struggle.

“It’s hot; I’m still cooling down right now,” Korda said. “I’m pretty happy with my first round in the conditions.

“It definitely takes a toll on you, the Texas heat.”

Auston Kim, who posted a one-under-par 71, said the heat had been more of a challenge than anything the twists and turns of the PGA Frisco layout had offered.

“I think the most difficult thing is dealing with the heat,” Kim said.

“There were times I had to lock in really hard just because the heat is taking a toll on you. You kind of want to just get into a daze and it’s hard to focus.

“The heat was probably the hardest part, and then hitting the fairways. I had to chop it out of the rough twice today, including on the last hole.

“I thought I was going to make double for sure, but I managed to make a really good bogey.”