Americans Angela Stanford and Cristie Kerr plus Hee Young Park also had 68s in the $1.3 million event at the Tanah Merah Country Club.

Ochoa got off to a fast start, shooting three birdies for a 33 on the front nine. The Mexican cooled off as wind picked up, leading to two bogeys before birdies on two of the last three holes.

"I'm really happy with four under," Ochoa said. "I left some out there, but hopefully I'll get them tomorrow." Four players were one shot off the lead, including No. 4 Ai Miyazato of Japan, who won last week's season-opening LPGA Thailand.

Several players said the swirling wind made play more difficult in the afternoon.

"When we started it was blowing one direction and as it picked up it started to change direction," Stanford said.

"It was a little tricky coming down the stretch today." Kerr got off to a rough start, with bogeys on two of the first three holes, but she finished with a flourish, birdying five of the last six holes to finish with a 31 on the back nine.

Last year's winner Jiyai Shin of South Korea shot a 1-under 71 while American Michelle Wie was four stokes from the leaders after a 72.

Singapore's 16-year-old Joey Poh, who won an amateur tournament to qualify, was in last place after an 82.