Thitikul grabs two-shot lead, Ruffels hanging tough

Rising star Atthaya Thitikul birdied five of the final seven holes in a round of 7-under 65 to grab the halfway lead in the LPGA Tour's Americas Open.

But not far behind lurks world No.1 Nelly Korda, who had her LPGA record-tying five tournament winning streak halted last week, and rising Australian star Gabi Ruffels.

Thitikul, who is playing in her third event this year because of an injury to her left thumb, had a bogey-free round at Liberty National while playing in a group that included Korda and Ayaka Furue of Japan.

The 21-year-old from Thailand, who was last year's winner of the Rolex Vare Award for lowest scoring average, is two shots ahead of first-round leader So Mi Lee of South Korea and three in front of Korda, Ruffels, Mao Saigo (Japan) and fellow Thai Ariya Jutanugarn.

Another large group was four shots back, including Jutarugarn's sister, Moriya. Americans Andrea Lee and Megan Khang and Furue are also at 5 under in the event that lost defending champion Rose Zhang after three holes to an intestinal problem.

"When I can come here, play in Chevron, be able to play golf again, it's just like click, and change my mind," Thitikul said.

"Just be able to play golf it's good enough for me. It's just go enjoy. Just do the best that you can do out there."

Thitikul, who has two LPGA career wins in 2022 and already pocketed $US3.85 million ($A5.7m) in career earnings, finished 12th in the Chevron and missed the cut by a stroke in the Cognizant Founders Cup last week.

She switched putters this week and it clicked in the second round. It could have been better, too. A long birdie putt at No.18 lipped out.

"I played with Atthaya today and my round felt like poop compared to hers," said Korda, who shot a 68, two shots better than her opening round.

"She's playing phenomenal golf the past two days. I'm happy to be in it; three back at the halfway point, but hopefully I can give it my best."

In her recent winning streak that Zhang snapped last week, Korda trailed by five shots at the Seri Pak Championship, by four at the Ford Championship and six strokes in the T-Mobile Match Play, where the field was cut after the third round. She won them all.

"If you're not hitting it well and not giving your self chances, you're never going to capitalise on this," Korda said. "Hopefully everything is flowing for me. Going to go practise a little now after my round and try to get things a little bit more dialled in for the weekend."

Ruffels, who opened with a 68, had three birdies and a lone bogey - her only one in the tournament - in her 70.

The LPGA Tour's rookie-of-the-year leader is in hot form and finished third at last week's Cognizant Founders Cup, also in New Jersey, before successfully qualifying for the US Open.

Sarah Kemp at four under is the next best Australian after shooting a brilliant 5-under 67. Kemp is tied 15th, one ahead of Karis Davidson (71-70) and world No.8 Minjee Lee (69-72).

Lee (66) and Saigo (68) were Thursday additions to the field because of late withdrawals. They found themselves at the top of the leaderboard after 18 and were still there Friday. Lee had a 71, one shot more than Saigo.