Joanne Morley, an eight-year LPGA Tour veteran, shot a 4-under 67 to grab second place at 5-under-par 137. Shi Hyun Ahn, Karen Stupples and Johanna Head share third place at 3-under-par 139.
Sorenstam, who returned to this event after a five-week break, cruised through her round. She dropped a 7-iron within 10 feet of the cup at the third and drained the birdie putt to move to minus-6.
However, the Swede three-putted for bogey at the fourth for her lone mistake of the round. Sorenstam ran off four consecutive pars from the fifth.
At the par-4 ninth, Sorenstam dropped a pitch-wedge 7 feet from the hole. She converted that birdie try to get back to 6 under.
Sorenstam, the 2002 champion here, ran home a 25-footer for birdie at the par-4 11th. She converted a 6-foot putt for birdie at the 14th at Cedar Ridge Country Club to climb to 8 under.
Sorenstam parred three straight holes before a poor tee shot at the last. She lost her tee ball right into heavy rough.
The women's world No. 1 hacked a fairway wood out of the thick rough, but missed the green long and left. Sorenstam pitched to 7 feet and sank the par putt to remain three strokes clear of the field.
'I'm very pleased to be at 8 under after two rounds here,' Sorenstam said. 'I didn't really expect that coming into this week. I thought today I had some great iron shots. I didn't miss a lot of greens, maybe one or two at the most.'
Morley will be in unfamiliar territory in the final round. Her best standing after two rounds of a 54-hole event was in 1997, when she was in third place at the HealthSouth Inaugural event. She carded a final-round 74 to end up in a tie for fifth there.
The 37-year-old opened her round with a 6-foot birdie putt at the second. Morley rolled in back-to-back birdies from ninth to get to 4 under.
Morley stumbled to a bogey at the par-4 11th, but came back with a 4-foot birdie putt at the next to return to minus-4. She claimed second place thanks to a 12-foot birdie putt at the 14th, before parring her final four holes.
'I wasn't so hot with my irons today, but they were good enough to actually find the green, and I got them pin-high,' stated Morley. 'I just holed some putts over the last two days and that's really been the difference.'
Christina Kim, the first-round leader, stumbled to a 4-over 75. She stands in a tie for sixth at 2-under-par 140. Mikaela Parmlid (71) and Kelli Kuehne (72) stand alongside Kim at minus-2.
The cut line fell at 7-over-par 149 with 78 players moving on to the weekend. Among those surviving on the number was amateur star Paula Creamer. She has made the cut in all seven LPGA events she has played in this year, with her best finish a tie for second at the ShopRite LPGA Classic.