China's Yu Liu has joined Celine Boutier of France at the top of a crowded US Women's Open leaderboard after the third round in Charleston, South Carolina.
Boutier drove the ball with unerring accuracy on Saturday en route to a 69 while Liu recovered from an early bogey to pile up six birdies and card a five-under-par 66 that matched the best score of the day.
The pair lead on seven-under 206 with Americans Lexi Thompson (68) and Jaye Marie Green (68) and Japan's Mamiko Higa (71) one stroke behind at Country Club of Charleston.
Best-placed Australian Minjee Lee sits four shots off the pace at three under after a round of 70. Brisbane's Katherine Kirk is two over and WA's Hannah Green well back at eight over.
Liu was stunned to be co-leader in her debut at the tournament.
"I think this is something that's really out of my expectations because it's only my first ever US Open," said the 23-year-old from Beijing.
"I was just happy to make the cut and being able to play the weekend."
No Chinese woman has won the US Open, while if Boutier triumphs she will be the second from France, after Catherine Lacoste in 1967.
"I was hitting the ball pretty good and pretty straight. Then when I was missing a couple of greens, my short game was there to save me," said Boutier, who made a clutch 20-foot putt to salvage bogey at the 16th hole after she had duffed a chip.
"I tried not to pay attention (to the leaderboard) because it gets me really stressed out. It was a little bit difficult at the beginning but then as the round went on, I kind of focused more on myself and my game."
Sunday's winner will take home $US1 million ($A1.4 million), the first seven-figure prize in women's golf.