Phatlum, playing late in the afternoon at the Columbia Edgewater Country Club, nipped Lexi Thompson by a shot for the first-round lead.
Thompson shot her 65 early in the day, a round highlighted by an eagle at the par-5 seventh.
Wie has started 65 tournaments without a victory after coming onto the LPGA Tour as a young sensation. She put together a bogey-free round that included birdies on five of her first 10 holes.
The current teen superstar of women's golf, 17-year-old amateur Lydia Ko, is not playing in this event after winning the Women's Canadian Open last week for the second straight year.