I.K. Kim led the U.S. Women's Open after the morning session of the second round Friday.
The South Korean shot a 3-under 69 for a 7-under total. Ha-Neul Kim, the first-round leader, had a 77 to fall back to 1 under.
Top-ranked Inbee Park, who came in at 5 under, is playing the afternoon session. Park is trying to make history by winning the year's first three majors. No one has ever done that in a season with at least four majors.
American Lizette Salas shot a 72 to stay at 4 under.
Players were surprised Thursday to arrive at Sebonack to find the tees moved up and the weather calm - an easy course by U.S. Open standards. On Friday, the setup and the conditions were more what they expected: The winds picked up and some pins were tucked into uncomfortable spots.
''Anything under par I thought was going to be a great score,'' I.K. Kim said.
She seems to thrive under the demands of this tournament. Kim finished in third or fourth place three straight years from 2008 to `10.