Minjee Lee has rocketed to the top of the leaderboard with a supreme second round at the mega-rich US Women's Open in North Carolina.

Australia's in-form star fired a five-under-par 66 to make up three shots on first-round frontrunner Mina Harigae (69) and share the halfway lead with the American.

Lee and Harigae are nine-under for the championship, holding a two-stroke buffer over Korean Hye-Jin Choi (64) and Sweden's three-time major winner Anna Nordqvist (68).

Chasing a second major in 11 months and second LPGA Tour victory in three starts, Lee collected another six birdies on Friday and had a chance to tie the low 36-hole total at a Women's US Open.

But the 26-year-old world number four left her eight-metre birdie putt short on the last hole at Pine Needles Golf and Country Club.

Lee had only one blemish in her round, dropping a shot on the par-4 14th, but bounced straight back with successive birdies on 15 and 16 to be firmly in the mix for the record-setting $US1.8 million ($A2.5 million) winner's cheque.

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"Same as yesterday — my putting was really solid again. Even when I was in tough spots, I still managed to get up and down," Lee said.

"I just tried to take advantage of my birdie opportunities and that's pretty much what I did today."

Total prize money on offer this week is a staggering $US10 million ($A13.7 million), the biggest purse in women's golf history.

Lee said it was vital not to get ahead of herself over the weekend.

Lee is not the only big name in the hunt.

World number one Jin Young Ko (67) charged to six under with four birdies and an eagle to be trailing the co-leaders by three shots. She's tied in fifth with Swedish amateur sensation Ingrid Lindblad (71).

Lee's countrywoman Hannah Green isn't out of it either after posting an even-par 71 to stay at one under.

Grace Kim (72) is three over, but fellow Australians Sarah Kemp (70, four over) Gabi Ruffels (75, seven over) missed the cut.

AAP