Rosie Jones notched a 2-under 70 to move into a share of second place at 4-under-par 140. She is joined there by Meg Mallon. Michelle Redman is one stroke further back at minus-3.
Sorenstam got off to a hot start as she dropped a sand-wedge within four feet to setup birdie at the first. The Swede was unable to get up-and-down on the fourth at El Caballero Country Club for her first bogey of the round.
The top player in the women's game dropped in a 6-foot birdie putt at the ninth to get to minus-5. However, Sorenstam three-putted to a bogey at the very next hole.
Things turned around quickly from there. Sorenstam knocked an 8-iron within 8 feet for birdie at the 11th and came right back with a birdie at the next. On 12, she nearly holed her third shot but settled for a kick in birdie.
Sorenstam lost her drive left off the par-5 17th tee. After a punch out, she dropped her third shot within 1-foot for birdie. That got her to 7 under, but she bogeyed the last after losing her drive right.
'You cannot take anything for granted,' said Sorenstam. 'This course really keeps you on your toes. You have got to stay focused, hit one shot at a time. You are looking at some holes as a birdie hole, and you walk away with a par, and that's what makes it hard here.'
Sorenstam, who was inducted into the LPGA and World Golf Halls of Fame last year, is looking for her 50th win on the LPGA Tour. That would tie her with Louise Suggs for fifth on the all-time wins list.
'I do think about those things,' said Sorenstam of the records. 'However, once I get to the golf course that particular day, I just let things happen. (On Sunday), I hope to straighten out my swing, try to hit the fairway, try to hit the green and make the putts. The outcome will be whatever it's supposed to be.'
Jones opened her round two strokes behind Sorenstam. She began her round by draining a 20-footer for birdie at the second. However, she stumbled to a double bogey at the very next hole to drop off the pace.
The six-time Solheim Cup performer bounced back to birdie the sixth from 12 feet out. However, Jones tripped to another bogey at the next.
Around the turn, Jones climbed back into contention. She sank a 3-footer for birdie at the 12th. She capped her scoring by holing a 9-iron from 126 yards out for eagle at the 15th. She parred out to finish at minus-4.
'It is easier to lose shots here than to pick them up,' said Jones. 'You get on the wrong side of the hole or get a bad read or bad bounce and all of a sudden you are looking at something coming back.'
Mallon started her round on the back nine with back-to-back birdies from the 10th to quickly climb to minus-5. She stumbled to a bogey at the 14th before cruising to four straight pars.
On the front side, Mallon tripped to a bogey at No. 1. She responded in fine fashion with consecutive birdies from the second. Mallon ended the streak with a bogey at the fourth. She ended with five pars in a row to cap a round of 71.
Michelle Ellis fired a 4-under 68, one of just four rounds in the 60s, to move into a tie for fifth at 2-under-par 142. Catriona Matthew (70) and Jill McGill (73) join Ellis at minus-2.
Jenny Rosales, Mi Hyun Kim, Betsy King and Carin Koch are one stroke further back at 1-under-par 143.
The cut line fell at 7-over-par 151 with 72 players advancing to Sunday's action.