Play was suspended due to darkness with 15 players remaining on the course. Those players will return to the course at 10:00 a.m. (ET) to complete their rounds and the second round will start as scheduled at 10:00.
Meg Mallon and Jill McGill share second place at minus-3. Karen Stupples, who won the season-opening Welch's/Fry's Championship, carded a 2-under-par 70 Friday. She shares fourth place with Ashli Bunch, Jeong Jang and Rosie Jones.
Sorenstam, who won by four strokes here last year, opened quickly with a birdie at the par-3 10th, her first. She stumbled to a three-putt bogey at the par-4 13th at El Caballero Country Club to drop back to even-par.
The top player in the women's game got back into red figures with a 12-foot birdie putt at the 15th. Sorenstam ran off three straight pars to head to he front side at minus-1.
Around the turn, Sorenstam rolled in an 8-footer for birdie at the par-5 first. She then notched five consecutive pars before closing with a flourish.
The Swede got up-and-down for birdie at the par-5 seventh and made it two straight when she sank a 31-footer for birdie at the eighth. Sorenstam parred the last to hang on to first place and share the course record of 68 set eight times previously.
'I hit a lot of good shots today,' said Sorenstam, who won this event in 2001 and 2003 with a second place finish in 2002. 'I mixed them with a few bad ones, but when I did hit a bad one, I was able to make an up-and-down.
'I putted real well too. I had a good feel on the greens, and I had a chance to make a lot of birdies and obviously that helps.'
Mallon dropped a 5-iron within 15 feet at the second to set up her first birdie. She came back with an 8-foot birdie putt at the fourth to move to minus-2.
She closed her opening nine by dropping in a six-footer for birdie at the ninth. Mallon was unable to save par at the 11th after missing the green, but gained a share of second with a 5-foot birdie putt at the last.
'I hits 16 greens today and that was really the key,' said Mallon. 'I actually had some closer putts than the ones I made that I missed, but just because I was where I was and position of the hole, they were difficult putts. But overall, I managed my game really well.'
McGill had an up-and-down day. She birdied the first, but stumbled to a bogey at the very next hole. She picked up another birdie at the par-4 fifth. However, McGill faltered to another bogey at the seventh.
The 32-year-old bounced right back to birdie the eighth as she ran home a 24- foot putt. McGill drained another lengthy birdie putt, this one from 30 feet out, at the 13th to move to minus-2.
McGill missed the green at the 15th and that led to her third and final bogey of the round. She closed with back-to-back birdies from the 17th to share second place with Mallon.
'My putter hasn't been working for about nine years, but it was nice to see it working today,' McGill said. 'It felt pretty good. I worked with my coach on Wednesday and got a little training device to use from another guy. I just envisioned it all day and it really helped.'
Michele Redman, Angela Stanford, Young Kim and Betsy King share eighth place at 1-under-par 71. Aree Song, the runner-up last week at the Kraft Nabisco Championship, stands at even-par through 16 holes. Nine other players are at even-par and are all finished their round.