Miyazato, a one-time winner on the LPGA Tour, finished second at this tournament a year ago.
There were 22 players within three shots of the lead with So Yeon Ryu and Angela Stanford sharing second place at 66.
Miyazato parred the first six holes of the Pinnacle Country Club course and then went on her birdie run that vaulted her into the lead. Her only victory on the circuit came at the 2012 Safeway Classic.
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