Ochoa held off a hard-charging Suzann Pettersen in the final round for her first win of the season.
Annika Sorenstam shared eighth place behind Ochoa and held on to the top spot in the rankings, but her lead over Ochoa is just 0.75 average points.
To make room for Ochoa's move, Karrie Webb dipped to third. Cristie Kerr and Paula Creamer remained steady at fourth and fifth.
Ai Miyazato and Juli Inkster exchanged places with Miyazato up a notch to sixth.
The next eight spots remained unchanged with Jeong Jang, Shiho Ohyama, Se-Ri Pak, Pat Hurst, Hee-Won Han, Mi Hyun Kim, Stacy Prammanasudh and Julieta Granada holding steady in the eighth through 15th positions.
Jee Young Lee inched up one to 16th, while Morgan Pressel dipped a spot to 17th. Michelle Wie, Yuri Fudoh and Seon-Hwa Lee held on to the 18th through 20th positions.
Pettersen made a big move in the rankings with her runner-up finish. She jumped 26 places to No. 32.