World No.1 Nelly Korda has been sent packing early from the Women's PGA Championship in another shocking fade-out after a dominating run.

A stroke behind first-round leader Lexi Thompson after an opening 3-under 69, Korda shot an 81 in the second round to miss the weekend cut by a stroke.

The round was the highest in a major championship by a top-ranked player since the inception of the ranking in 2006.

Korda also missed the cuts in the US Women's Open - opening with an 80 - and the Meijer LPGA Classic in her last two starts after winning six of seven events, a run that started with a record-tying five straight victories.

"It's just golf recently for me," Korda said. "No words for how I am playing right now. I'm just going to go home and try to reset."

While Korda struggled in the warm afternoon conditions that sped up tree-lined Sahalee Country Club, Sarah Schmelzel and Amy Yang shared the lead at 6-under 136. Schmelzel had a 67 in the morning, and Yang shot 68 in the afternoon.

Korda bogeyed the first four holes and also dropped strokes on Nos.6 and 9 in a front-nine 42. She bogeyed Nos.11 and 14, had a double bogey on the 15 and made her lone birdie of the day on 18.

One of the big movers was Steph Kyriacou. The 23-year-old, who opened with a 74, shot a 69 to move to within five off the lead.

At one under, the Sydneysider is now tied 12th. Kyriacou's card included three birdies, two bogeys and an eagle on the 18th.

Minjee Lee (74-72) is the next best Australian at two over, with Gabriela Ruffels (74,74), Grace Kim (73-75) and 2019 champion Hannah Green (71-77) all at four over.

The 30-year-old Schmelzel, who is winless in six seasons on the LPGA Tour, made a 10-foot birdie putt on the par-3 17th hole and stayed aggressive on the par-5 18th, knocking her three-wood short of the green and chipping to a foot for a tap-in birdie and the low round of the championship.

"Just staying really patient out there and aggressive off the tee was kind of our game plan this week," Schmelzel said. "I drove (the ball) really well, so fortunately able to take advantage of having some shorter irons in today."

Yang is searching for her first major title. Dealing with a back issue, she had the only bogey-free round of the tournament.

The five-time LPGA winner had no trouble with the firmness of the poa annua greens in the afternoon, successfully scrambling for par in all eight attempts. She hit her 97-yard third shot on 18 to a foot to set up a birdie.

"Fairways are so tight," Yang said. "It's very challenging out there."

Thompson (72) is two strokes back with fellow major champions Jin Young Ko (68), and Hinako Shibuno (70).

Starting on the back nine, Thompson turned in 3 under 33 to reach seven under, but made a double bogey on the par-5 second hole. Her second shot missed left, forcing a punch-out, and she three-putted for a seven. Thompson dropped another shot on the par-4 fourth.

The 29-year-old Thompson, who recently announced this season will be her last playing a full schedule, lost a playoff last week at the Meijer LPGA Classic. She hasn't won on the LPGA Tour since June 2019.

"You're going to hit some bad shots, maybe get penalised by the trees," Thompson said. "You just have to take your medicine with either pitching out or getting back into position."