Ochoa went through the first nine holes in just 29 shots

American Rosie Jones lies a stroke behind in third, with Scottish golfer Janice Moodie a further shot back in joint fourth with South Korea's Jeong Jang.

English player Samantha Head was a further shot back after a 69 while Laura Davies, South Korean Se Ri Pak and Australian Karrie Webb were in a group of nine players tied for seventh.

Sweden's Annika Sorenstam, returning to competitive action after a two-week rest, had a 72 and lies in joint 31st.

LEADERBOARD -6 J Inkster, L Ochoa -5 R Jones (USA) -4 J Moodie, Jeong Jang -3 S Head -2 K Robbins, J Rosales , P Hurst, Soo-Yun Kang, N Taylor, R Teske, L Davies, K Webb , Se Ri Pak

Ochoa hit four birdies and eagle in her first seven holes to reach the turn in 29, only the 10th player to do so on the European Tour.

The 22-year-old from Guadalajara could not match that on the homeward nine, where her one birdie was more than cancelled out by two dropped shots, but she was nevertheless delighted with her round.

"After the 29, of course you want to go lower, but I knew the back nine was tougher," she said. "And my two bogeys were from difficult positions so were good bogeys."

The 43-year-old Inkster snatched a share of the lead with an eagle at the 18th, where she hit a five iron to three feet.

That added to her six birdies with a double bogey at the 15th - where she drove out of bounds - the only blip on her card.

Defending champion Sorenstam also went wayward with her tee-shot at the 15th and dropped two shots.

Davies was another to incur a double bogey - at the 18th - and she felt hard done by as it came about when she hit her second shot into an arrangement of red flowers by the green.

"I wasn't allowed a free drop, but it's a flower bed and that's not normal on a golf course," said the two-time champion.

"It should have been marked Ground Under Repair and I should have been given a drop."

In anger, Davies took two to get out of the flowers, and then duffed a third chip before holing from 10 feet for a seven to blight a round which had seen seven birdies.