The Norwegian dropped three shots over the first five holes but had three birdies and just one more bogey the rest of the way for a 6-under total of 210. The trio of Azahara Munoz, Sun Young Yoo and Carlota Ciganda were four shots back heading into the final round.
One of Pettersen's bogeys came on the par-3 second, which she aced on Friday.
"On the second, I kind of made a little amateur mistake trying to get too cute on the tee ball and left myself with a very tough up and down," Pettersen said. "I just couldn't get it going and made a few errors. Today was a tough day for me. It was all about hanging in there and trying to bring it back to where I started."
Pettersen birdied par-5s on the eighth and 13th before another bogey at the 17th. She finished off with a birdie on 18 for a three-day total of 6-under.
I could easily have lost it out there today," Pettersen said. "It was — you know, some days are easy, some days are not that easy, some of the times you see everything you're going to do right in front of you.
Munoz shot a 69 at the Sunrise Golf and Country Club to climb up the leaderboard, while Yoo and Ciganda both shot 72.
Munoz has just one top-10 finish on the LPGA Tour this year, but won a Ladies European Tour event in France in September.
"It's fun finally being in contention and being in one of either the leading group or second leading groups," said Munoz, who was second in Taiwan in 2011. I'm just going to go out there and keep playing like I am."
After her poor start, Pettersen recovered with birdies on No. 8 and 13 before three-putting for another bogey on 17. But she finished with a birdie to carry a bit of momentum into Sunday.I could easily have lost it out there today," Pettersen said. "Obviously nice to finish on a good note. This is far from over.
