'I'm very pleased with the way I played today,' said Sorenstam. 'Tomorrow I've just got to play solid golf. I'm going to continue to shoot in the 60s and see how low we can go.'
Rosie Jones, who shared the lead with Sorenstam after round one, carded a 1- under 71 to finish alone in third at 11-under-par 133. Juli Inkster was two shots further back at 9-under-par 135.
Sorenstam has proved that she is ready to win in her first LPGA start since her historic appearance at the PGA Tour's Colonial. The Swede, who won this event last year in record-setting fashion, hit her tee shot to four feet at the par-3 third for her first birdie of the day.
She followed that up with a birdie at the very next hole and coasted at even-par until a birdie at the par-4 11th. Sorenstam found trouble soon after with a pair of bogeys starting at the par-3 12th but countered with a remarkable stretch to close her round and secure the 36-hole lead.
'I told my caddie, 'I've had enough. I'm playing great, I've had a lot of great shots. Let's get this turned around. There's five more holes, let's just go get five birdies,'' said Sorenstam. 'And that's what happened.'
Sorenstam picked up the first of five consecutive birdies at the par-5 14th. She closed her round in style, and in a good position to take home her 44th career victory on the LPGA Tour.
McKay shot a brilliant round of 64 to move into second place. She started with a birdie at the second and ran home a long birdie putt at the very next hole. She made it three in a row with a birdie at the fourth and added a birdie at the eighth to reach 10-under.
The 28-year-old caught fire on the back nine with five birdies to pull within two of Sorenstam.
Despite a bogey at the par-5 first, Jones contended for the lead throughout the round. However, she could not match Sorenstam's torrid finish and stands five shots off the lead.
'I got away with something today,' said Jones. 'I didn't hit the ball well at all. I feel like I could have shot 3- or 4-under. I just didn't do it.'
Becky Morgan shot a 3-under 69 to finish alongside Angela Stanford at 8-under-par 136. The duo was followed by Mi Hyun Kim at 7-under-par 137.
Tracy Hanson, Catriona Matthew, Christina Kim and Heather Bowie finished tied for eighth at 6-under-par 138.
The 36-hole cut fell at 3-over-par 147. Among those who failed to qualify for the weekend were Grace Park and Betsy King.