The Japanese is aiming to go one better than last year at Pinnacle Country Club when she came in second behind compatriot - but no relation - Ai Miyazato.
Mika Miyazato, winner of last year's Safeway Classic, holds a one-shot lead over American Angela Stanford and Korea's So Yeon Ryu who both had opening rounds of five-under 66s.
Miyazato, 23, shot six birdies, including consecutive efforts on the 10th and 11th holes on her way to taking her position at the top of the leaderboard.
"I had so many good shots today. Yesterday, I worked hard on short putts because I changed putters in the Bahamas," Miyazato said. "So I practiced a lot yesterday and that gave me so much confidence today."
Miyazato's best finish so far this year on the LPGA Tour was a tie for fourth in the Bahamas.
Stanford, runner-up in 2009, had three birdies on the back nine after a lone bogey at the 12th to stay in touch with the leader.
"Today seemed to be fairly consistent ball striking wise," Stanford said. "Then putting was pretty good, too. I just seemed to have a lot of opportunities, so those are good days.
"It seems like the fairways are firm and fast, which is usually good for me, but the greens are still kind of receptive and I thought the pin placements were pretty accessible today."
Ten players were behind the leading trio at four-under, including Stacy Lewis.
World number one Inbee Park was four off the pace, while defending champion Ai Miyazato was down in a tie for 96th after shooting a two-over 73.
- Sports & Recreation
- Mika Miyazato
- Angela Stanford