Michele Redman and A.J. Eathorne each carded rounds of 2-under 69 and are knotted in second place at 4-under-par 138. Shi Hyun Ahn (70) and Nicole Perrot (69) share fourth place at minus-3.
Saturday's second-round action went off without a hitch after heavy rain washed away Friday's play. The schedule now calls for 36 holes on Sunday to complete the tournament.
Annika Sorenstam's opportunity at history is in jeopardy as she has a chance to become the first player in LPGA Tour history to win six consecutive tournaments. She opened with a 5-over 76 on Thursday and was in danger of missing the cut.
She rebounded on Saturday with a 4-under 67. Sorenstam is tied for 26th place at 1-over-par 143 and with 36 holes to play on Sunday, the top player in the game knows anything can happen.
'You got to stay positive out there. That is what I do when I play,' said Sorenstam. 'I think tomorrow is going to be good for 36 holes. I have done well in the past with that, so I look forward to it.'
Sorenstam will have a long way to go to catch Kerr.
Kerr broke into red figures quickly at the 11th, her second hole. She hit a pitching wedge to 20 feet and drained the putt. Kerr birdied the 14th when her 9-iron stopped within tap-in range, then made it two in a row with another short birdie putt at the par-5 hole.
Kerr three-putted for a bogey from 35 feet at the 16th, but closed her front nine with a birdie. She hit a 9-iron inside 3 feet for birdie No. 4 and a 3-under 32 on her front side.
At the par-3 second hole, Kerr hit a 6-iron to within 15 feet to set up birdie. The 27-year-old made it back-to-back birdies at the par-3 third as she narrowly missed an eagle with her chip from short of the green. She tapped in for birdie to reach 8-under par for the championship.
Things fell apart toward the end of Kerr's round. At the par-3 fifth, Kerr pulled an 8-iron and left it 35 feet short. She three-putted for a bogey, then dropped another shot to par at eight. Kerr hit a terrible drive that forced her to chip out to the fairway. She knocked an 8-iron on to the green, but missed her par putt.
Despite the late-round miscues, Kerr takes the lead after the second round for the 10th time.
'I think I got mentally tired at the end of the round. It was a long day,' admitted Kerr. 'I will get plenty of rest tomorrow. See if I can hit it a little straighter coming in.'
Kerr will be looking for her first win this season and fifth overall. To do it, she'll have to be patient since this a rare occurrence with 36 holes on Sunday.
'We are going to have 10 hours plus of golf tomorrow, you have to be prepared for that,' said Kerr. 'It's not only a test of your physical game but of your mental probably equally tomorrow.'
Redman mixed three birdies and a bogey for her 69 on Saturday, while Eathorne tallied four birdies and a pair of bogeys.
Jill McGill (72) and Wendy Doolan (71) are tied for sixth place at 2-under-par 140. First-round co-leader Silvia Cavalleri (74), Jimin Kang (72), Mi Hyun Kim (72), Beth Daniel (71), Catriona Matthew (71) and Rosie Jones (70) share eighth at minus-1.
Cavalleri's fellow first-round leader, Catrin Nilsmark, struggled badly on Saturday. She shot a 13-over-par 84 and missed the cut by five shots.
The 36-hole cut fell at 4-over-par 146 and among the notable players who will not be in action for the final two rounds were: Christina Kim (148), Betsy King (153) and defending champion Se Ri Pak (154).