Inkster -- a Hall of Fame member who at 47 is in her 24th year on the LPGA Tour -- shot a 5-under 66 Friday to finish 36 holes at 8-under 134 -- tied with Shi Hyun Ahn.
"It's fun being out here with the younger players," Inkster said. "I think it keeps you young, keeps you going, keeps you motivated."
Ochoa, who recently captured her first major title at the Women's British Open, shot a 65 to move into third place at 135.
"I had an easy day," Ochoa said. "I hit it really close to the hole and had a lot of birdie chances. I'm in good position for the weekend."
Ochoa was tied with Kimberly Hall and first-round leader Laura Diaz.