Ochoa is looking for a first major title at St Andrew's
-6 L Ochoa (Mex)
-5 W Ward (US), C Matthew (Sco)
-3 A Sorenstam (Swe), S Steinhauer (US), Y Fudoh (Jpn), R Hudson (Eng), K Icher (Fra)
Lorena Ochoa shot a level-par second round to stay in front at the Women's British Open, while Scotland's Catriona Matthew charged into contention.
World number one Ochoa maintained her bid for a first major with a 73 to stay six under, one clear of Wendy Ward (70) and Matthew, who shot a superb 68.
Former number one Annika Sorenstam moved up to three under, in a group with England's Rebecca Hudson.
Michelle Wie made five bogeys and one double bogey in a round of 80.
The 17-year-old managed her only birdie of the day at the last but crashed out of the event on seven over par.
"I'm still positive about it - my driving was awesome," she said.
"I just didn't convert with my irons and my putter and it all came down to that. I must have been in eight divots, but no excuses. Today was not my day."
The star of the day was home favourite Matthew, who shot a blemish-free round and moved to within a stroke of the lead when Ochoa bogeyed the last.
"You would not be normal unless you were nervous, but I'm playing well so there's no reason why I can't have two more good rounds," said Matthew.
"It was a great feeling having people cheering you onto the greens. In the States you don't get the home support - and obviously it would be great to win."
Hudson built on her opening round of 70 with a 73, although she too dropped a stroke at the 18th.
American Solheim Cup player Ward moved into contention with a 70, while Sorenstam and defending champion Sherri Steinhauer will be a threat on three under.
"I'm thrilled that I'm playing well," said the 36-year-old Sorenstam, who is still recovering full fitness after suffering a ruptured and herniated disc in her back.
"I'm starting to get my natural draw back. I haven't really seen that in about 19 months and it's something you need on this course."
Extensive coverage of the Women's British Open can be seen on BBC TWO and the BBC Sport website. Click on the 'Golf on the BBC' link for times.