Munoz is not only seeking her first tour triumph, she is looking for her first Top 25 finish. This is only her third appearance on the tour and her best finish to date has been a tie for 27th.
This is the first tour event since the death of LPGA member Erica Blasberg. Many players wore black ribbons in her honor.
"The course is playing tough, but I just hit every fairway and pretty much every green," said Munoz, who was in the first group out off the 10th tee. "The only green I missed, I holed a bunker shot, so that was nice."
Munoz opened a tour event in Mexico two weeks ago with a 65 but struggled over the next two rounds and fell out of contention.
Jiyai Shin, who took over the No. 1 world ranking after the retirement of Lorena Ochoa, opened with a 70. Michelle Wie had a 72.