Neumann, winner of the 1988 U.S. Open, used precise putting and, over the difficult final four holes, a conservative strategy to forge a one-shot lead.
``I made some great putts,'' she said, ``and I think 4-under was about as good as it could have gotten today.''
Susie Redman, Kelly Robbins, Deb Richard and Se Ri Pak were tied for second at 68.
Sorenstam's collapse to a 6-over-par 77 was punctuated by a disastrous triple-bogey on No. 9.
Still, she did not rule out a comeback.
``This is just Thursday,'' she said. ``I know how to play this golf course.''
In other tournaments:
SENIORS: TWO SHARE LEAD Larry Gilbert and Dana Quigley, both career club pros before turning 50, shared a one-stroke lead after the first round of the Senior Players Championship at the Tournament Players Club of Michigan course in Dearborn.
Gilbert and Quigley each shot 5-under-par 67s over the 6,876-yard course.
South African John Bland and Dave Stockton were both at 68, one stroke better than Jack Nicklaus, John Schroeder, Vincente Fernandez and Larry Mowry.
PGA: HALLBERG EMERGES Gary Hallberg, who has missed the cut in his last 18 PGA Tour events, shot a 5-under-par 65 to take a one-stroke lead after the first round of the Quad City Classic at the Oakwood Country Club in Coal City, Ill.
Three golfers were tied at 66: Dave Stockton Jr., whose father won the event in 1974; Russ Cochran, whose lone tour victory was the 1991 Western Open; and former University of Iowa golfer Sean McCarty, who is making his PGA Tour debut.
GULFSTREAM: LEHMAN LEADS Tom Lehman, back in Britain where he won the Open championship last year, fired a 5-under-par 66 and took the second-round lead in the $1.34 million Gulfstream World Invitational in Loch Lomond, Scotland.