American Juli Inkster fired a bogey-free five-under 67 for a share of the first-round lead with last year's runner-up Suzann Pettersen at the $1 million Lorena Ochoa Invitational.
Inkster, 51, is seeking to become the oldest winner in LPGA Tour history. Beth Daniel was 46 when she won the Canadian Women's Open eight years ago.
South Korea's Meena Lee Thursday shot a first round four-under 68, and Scotland's Catriona Matthew was another stroke back in the 36-player field at Guadalajara Country Club.
American Michelle Wie was three strokes back at 70. Wie won this event in 2009. She was tied in a group that also includes Se Ri Pak, Maria Hjorth, Paula Creamer, Cristie Kerr and Sophie Gustafson.
Inkster's last victory on the LPGA Tour was at the 2006 Safeway International and the last time she converted a first round lead into a win was the 2003 Evian Ladies Masters. She has 31 career LPGA wins.
"I just put the ball on the fairway and made a couple putts," said Inkster. "I didn't have any bogeys, so it was nice."
World No. 2 Pettersen already has two LPGA Tour victories this year.
"I just stayed very calm," Pettersen said. "I like to be a perfectionist, and I went out with what I had and didn't try to overdo anything. I made some putts in the beginning and had some chances at the end."
World No. 1 Yani Tseng was alone in 34th after shooting a four-over 76. Defending champion I.K. Kim had a 72 on Thursday.
Kim closed with an eight-under par 64 last year en route to a tournament record 19-under par winning total.
She beat Pettersen by three shots, and donated half of her $220,000 winner's check to the Lorena Ochoa charitable foundation.