Cristie Kerr stands alone in second place at 5-under-par 67. Karrie Webb, like Sorenstam a two-time winner of this event, is tied for third place at minus-4 with Jeong Jang and Candie Kung.
This event is set aside for the top-30 money winners for the season. Due to three withdraws prior to the start of the event, No. 31 Stacy Prammanasudh, No. 32 Sherri Steinhauer and No. 33 Wendy Ward gained entry into the event.
Sorenstam, who won this event in 1997 and 2002, moved into red figures with a birdie at the par-5 third. She came back with a 9-foot birdie putt at the par-4 sixth at Trump International Golf Club to get to minus-2.
The Swede stumbled to a three-putt bogey at the eighth. Sorenstam bounced right back with a birdie at nine from 13 feet out to return to minus-2.
Around the turn, the women's world No. 1 dropped in a 10-foot birdie putt at the 12th to move to minus-3 for the first time. Sorenstam caught fire down the stretch.
The 34-year-old drained a birdie try at the 14th. She came right back with an up-and-down birdie at the par-5 15th to get to minus-5. Sorenstam moved out in front with a 9-foot birdie putt at 16.
Sorenstam, however, stumbled back to minus-5 with a bogey at 17. That was the first green she did not hit in regulation, and she was unable to get up and down for par. But she managed to take the overnight lead by converting a 7-foot birdie putt at the last.
'I'm very happy with my round. I think 6 under on this course any day is a good score,' said Sorenstam. 'I played very good today. I hit a lot of good tee shots, a lot of good iron shots. I thought I putted well, too. I'm very pleased with the round. I made two bogeys. I guess that happens, but other than that eight birdies on this course, I'm very pleased.'
Kerr got off to a quick start of her own. She dropped a wedge 15 feet from the cup to set up birdie at No. 1. Kerr came back with a two-putt birdie at the par-5 fifth.
The 27-year-old stuck a 6-iron inside 2 feet of the hole at six for her third birdie. Kerr posted five straight pars from there. She drained a long birdie putt at the 11th to move to minus-4.
Kerr, a two-time winner this season and two-time Solheim Cup performer, nearly holed a pitching wedge for eagle at 12. However, her second shot stopped within 6 inches of the cup and she kicked that in for birdie to get to minus-5. She missed some makeable birdie putts on the way in as she closed with six consecutive pars.
Laura Diaz stands alone in sixth place at 3-under-par 69. Jenny Rosales, Kim Saiki, Rachel Teske and LPGA Tour rookie of the year, Shi Hyun Ahn, are one stroke further back at minus-2. Grace Park is the last player in red figures at minus-1.
Meg Mallon, the defending champion, stood at 1 under par on the 18th tee. However, she lost two balls into the water right of the fairway and walked off with a triple bogey to finish in a tie for 16th place at 2-over-par 74.