Becky Morgan carded a 5-under 67 in the second round and is alone in third place at 8-under-par 136. American stars Rosie Jones (68) and Juli Inkster (69) are tied in fourth at minus-7.
Annika Sorenstam is looking to title at one of the few events she has never won. Of her 52 LPGA Tour victories, none are at this event, but the recent winner of the McDonald's LPGA Championship took steps on Friday to fix that.
Sorenstam fired a 6-under 66 and is in sole possession of sixth place at 6-under-par 138.
Saiki, the overnight leader, collected her first birdie of the round at the par-5 fourth hole when she sank a 25-footer. She added a 25-foot birdie putt at the seventh to make the turn at minus-2.
Saiki kept up her solid play with a 3-foot birdie putt at the 13th, but trouble loomed. She drove into the right rough at the 16th and could not get up-and-down for par. Saiki reclaimed the lost stroke with a 9-foot birdie putt to grab a share of the second-round lead for the first time since the event at Moon Valley in March of 2002.
'I felt really good about my round today; better than my round yesterday,' said Saiki, who is looking for her first victory on the LPGA Tour. 'My ball striking was a lot better today.'
Kung started on the back nine at Locust Hill and collected two birdies. She drained a pair of 15-foot birdie putts at the first and fifth, but ran into problems at the sixth.
She drove into trouble on the left and was forced to pitch out. Kung chipped on to the green for her third, but two-putted and left with bogey.
Kung came back with a 10-footer for birdie at the seventh to get into the clubhouse at minus-9.
'Overall, it was a pretty up-and-down day,' said Kung, who won collected three wins on tour last season. 'I like it right here after 36 holes. I'll just go out there, play the next two days and see how it goes.'
Morgan was flawless on Friday. She holed a 12-foot birdie putt at the 13th, her fourth hole of the round, and made from double that length for birdie at 16.
She parred out her first nine, but birdied three of her final seven holes to get within one of the lead.
'I hit the ball probably the best I have for three weeks,' said Morgan, who has played 80 consecutive holes at this tournament without a bogey. 'I just hit a lot of fairways and greens and stayed below the pins. I just put it in that position and holed a few putts.'
Mi Hyun Kim is alone in seventh place at minus-5. Jeong Jang (68), Catriona Matthew (70), amateur Paula Creamer (71) and defending champion Rachel Teske (70) are knotted in eighth place at 4-under-par 140.
The 36-hole cut fell at 3-over-par 147 and among the players who will miss the weekend are: Reilley Rankin (148) and Hilary Lunke (150). That does not bode well for Lunke as she defends her U.S. Women's Open title next week at Orchards Golf Club.