The American posted a 15-under 196 total, while South African Lee-Anne Pace had two eagles in a 61 to vault into a tie for second at 14-under with Canadian Brooke Henderson (67) and South Koreans Jenny Shin (63) and Park Sung-hyun (62).
Thompson also had a one-shot lead starting the final round at last week’s Manulife LPGA Classic in Ontario, and enjoyed a two-shot cushion with two holes to play before three-putting both to fall into a three-way playoff eventually won by Thai world number one Ariya Jutanugarn.
“I’ve been focusing on staying positive and making sure I do my routine on every shot and making sure I’m fully relaxed over my shots and in-between shots,” Thompson told Golf Channel.
“I sometimes over-think things. I’ve been focusing on staying positive.”
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Thompson, an eight-time LPGA Tour winner, did not try to force the issue in her third round.
“It was just a matter of staying patient,” she said. “I hit it well all day so it was just a matter of hitting the ball closer and making a few putts for birdie.”
Shin, whose lone LPGA victory came at the Texas Shootout last year, reeled off five straight birdies from the 10th hole, all from eight feet or longer as her putter caught fire.
“I started hitting it better and I just kept making the putts,” she said. “I wasn’t looking at the scorecard, wasn’t looking at the scores or anything.”
Pace also has one career LPGA win, back in 2014, and she is closer to doubling her tally after changing equipment recently.
"The last few weeks I struck my irons really, really well," Pace said. "I just actually changed the irons and it’s made all the difference."
While Canadian Henderson is in the hunt for her fourth Tour win, South Korean rookie Park is still searching for her breakthrough triumph.
(Reporting by Andrew Both in Cary, North Carolina; Editing by Peter Rutherford)
