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."