Ochoa shot a 4-under 68 to rally past Pettersen (66).
Ochoa blew a four-shot lead in the final round for the second time in three years at Superstition Mountain Golf and Country Club. But this time she survived, overtaking Norway's Pettersen with birdies on the 14th, 15th, 17th and 18th holes as a legion of fans chanted 'Viva Lorena!'
'I just tried to be patient,' Ochoa said. 'I had a lot of holes left.
'I was trying too hard. Sometimes when you try too hard, it's hard to make them.'
Ochoa, the tour's reigning player of the year, earned $225,000 for her 10th LPGA Tour victory. She finished at 18 under.
'She's maybe the best in the world right now,' said Pettersen, who had her career-best finish. 'She's just a very great player, and I think she raises the bar for all of us to chase her.'
The Mexican star opened the day with a four-stroke lead. But it disappeared as Pettersen then added another birdie on the seventh.
Two years ago, Ochoa blew a four-stroke lead with three holes to play and lost to Annika Sorenstam in a playoff.
'It is hard to tell you right now, but in 2005 it was a really tough day for me,' said Ochoa, a former University of Arizona player. 'It hurt me, and especially being here in Arizona, a special place for me. It was just a hard one.'
On Sunday, Ochoa watched her lead evaporate early.
Pettersen needed only five holes to erase Ochoa's lead, birdieing the second, third, fourth and fifth holes. Pettersen surged ahead when Ochoa bogeyed the par-4 sixth hole, missing a 4-foot putt.
'She put a lot of pressure on me,' Ochoa said.
Ochoa, who never trailed by more than a stroke, reclaimed the lead for good when she made a 10-foot putt on the par-3 17th.
Pettersen missed a 15-foot putt for birdie on the par-5 18th.
'I hit a good putt,' she said. 'I misread it.'
After Pettersen parred the 18th, Ochoa birdied the hole to wrap up the victory.
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