Thompson, who came under scrutiny from the golfing world following the penalty she received at the ANA Inspiration, fired a six-under round of 65 to take a one-shot lead in just her second start since the controversy at the year's first major.
“Yeah, it feels good,” said the still only 22-year-old. “I played very well. Had a slow front nine but gave myself some chances.
Thompson teed off the 10th hole and made the turn at even par before a birdie at the par-four first kick-started a stunning final nine of 30 that included five birdies in a row from the third.
“I hit some great shots and rolled a few good putts, so definitely helps out my confidence. It's just a tournament that I love to come back to. That always helps out, coming into a tournament that you want to play well in and you always look forward to coming to this venue, it helps out with the positive attitude.”
Thompson is one shot clear of fellow countrywomen Gerina Piller, Brittany Lincicome and Angel Yin.
World number one, Lydia Ko, and Queenslander Sarah Jane Smith lead the Australasians, the pair recording opening rounds of 67 to be in a share of fifth place and just two from Thompson's lead.
2015 champion, Minjee Lee from Perth, has also made a good start with a round of 68 to be tied for eighth alongside Victorian Su Oh, who finished runner-up in this event last year.
Katherine Kirk and another former Kingsmill winner, Karrie Webb, shot even par 71 while Sarah Kemp was the last of the Australasians with an opening three-over 74.
Ariya Jutanugarn was perhaps the surprise of day one when she could only manage an opening round of 72 to be in a share of 74th place.
AMERICAN TEENAGE ACE: ANGEL YIN
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