The South Korea produced a three-under-par round of 67, which featured consecutive birdies on holes five, six and seven, to move to seven under for the tournament at Aronimink Golf Club in Pennsylvania.

The world number seven, who is a past Women's PGA Championship runner-up, is two shots ahead of Brooke Henderson and Anna Nordqvist.

Henderson of Canada won this event in 2016, while Sweden's Nordqvist was the champion in 2009.

The Canadian produced the round of the day, a bogey-free 65, to move into a tie for second place.

Nordqvist shot 68 for the second day in a row.

Kim's compatriot, Park Inbee, who has gone five years without a major title, sits ominously in fourth, three shots off the lead.

Olympic champion Park is a seven-time major winner and made six birdies in a round of 66, underlining her ability to gain strokes after back-to-back even-par rounds.

Asian Games team gold medallist Bianca Pagdanganan of the Philippines shot 65 for the second day in a row, and like Henderson did not drop a single shot.

Pagdanganan is four under par, alone in fifth place, and could be dangerous after going 10-under through the last two rounds.

American Jennifer Kupcho is one of four players tied for sixth at two under.

Danielle Kang, another American player who entered the tournament as one of the favourites, finished with three bogies in a row and is on even par as a result, shooting 73.

New Zealand's former world number one Lydia Ko has fallen to a tie for 19th place after a disappointing 74 and is likely out of contention at two over.

Australian Hannah Green, last year's winner, is seven over par.

The final round will be played tomorrow.