Lexi Thompson shot a bogey-free five-under 66 to take the lead into the final round of the US Women's Open for the first time in her career with a one-shot edge over teenager Yuka Saso.

Thompson played a nearly flawless round in search of her first US Women's Open title in her 15th try after first competing as a 12-year-old amateur in 2007. She made three birdies on the front nine and two more on the back nine to overcome a four-shot deficit heading into the day and take the lead at seven under.

She was the first player all week to make par or better on every hole in the round.

"I struck it well all day, made a few good putts out there," Thompson said.

"And I guess probably just picking up the missed fairways or missed greens when I did, getting up-and-down or just getting it as far as I could out of that rough. So it's all about patience out on this golf course because there's going to be bad shots made."

Amateur Megha Ganne shot a 72 and was tied for third at three under with 2019 champion Jeongueun Lee6 of South Korea.

The 26-year-old Thompson hasn't won an LPGA Tour tournament in nearly two years and won her only major in 2014. She has four-top 10 finishes at the US Women's Open, including a runner-up to Lee6 two years ago in Charleston.

Thompson has been lurking around the leaderboard all week, shooting 69 on Thursday and 71 in the second round before the lowest round of her career at this tournament on Saturday.

"It's just a great golf course. That's how major championships should be," Thompson added.

"They should be longer, rough up thick and it's held up to its standards of being out there."

Saso, who has never finished better than sixth in an LPGA Tour event, will play in the final group on Sunday with a chance to join South Korea's Inbee Park as the only teens to win this tournament. Park did it at 19 years, 11 months, 17 days in 2008, which will be Saso's exact age Sunday.

Minjee Lee is Australia's best, tied for 55th after a disappointing 77 to be 10-over, with Hannah Green (78) a further three shots adrift.