Natalie Gulbis posted a 6-under-par 66 and shares third place with Nancy Harvey, Audra Burks and Lee Ann Walker-Cooper at Corning Country Club.
'Obviously I'm very happy with the way I played today and the way I finished,' said Sorenstam, already a two-time winner this season. 'I thought I hit the ball really well, I putted well. I believe I hit 18 greens, and I haven't done that in a long time. I feel really good about my game and obviously it feels nice to make a lot of birdies.'
Sorenstam, playing for the first time in three weeks, got off to a a good start as she rolled in a 25-foot birdie putt at the first. However, she tripped to a three-putt bogey at the very next hole.
The Swede two-putted for birdie at the par-5 fifth. At the next, she dropped a wedge within 4 feet to set up birdie. Sorenstam again had putting trouble at the seventh, where she three-putted for bogey.
The Hall of Famer came right back to birdie the eighth to get back to minus-2. Around the turn, Sorenstam caught fire. She drained a 26-foot birdie putt at the 10th and came right back to birdie the next from 8 feet.
Sorenstam capped a run of three straight birdies when she sank a 4-footer at the 12th to get to 5 under. She drained her eighth birdie of the day at the 15th.
She climbed into a share of the lead at minus-7 when she sank a 4-foot birdie at the 16th. Sorenstam remained tied for first as she parred the final two holes.
Neumann, who is winless since 1998, opened with a two-putt birdie on the second. He came right back with 15-foot birdie at the next to quickly get to minus-2.
The 1988 U.S. Women's Open winner again two-putted for birdie at the fifth. She moved to 4 under with a 40-foot birdie putt at the seventh and came back to birdie the next.
Around the turn, Neumann drained a 45-foot birdie putt at the 12th. She came back with another lengthy birdie putt at the next to get to 7 under. She stumbled to a three-putt bogey at the 16th, but came right back to birdie the 17th for her share of first place.
'You do feed off each other, when you see someone else making putts or hitting good shots,' said Neumann, who played with Meg Mallon (69) and Catriona Matthew (67). 'I think it just really keeps you focused. It was sort of a relaxing day for all of us out there. We all played pretty solid golf and made some putts out there. So it was a nice day for all of us.'
Matthew was joined at 5-under-par 67 by Michelle Estill, Sherri Steinhauer and Hilary Lunke. Mallon stands in a tie for 18th at 3-under-par 69.
Juli Inkster, the defending champion, posted a 1-over-par 73 where she stands in a tie for 81st.