MIAMI • American Lexi Thompson is counting on the support of her brother Curtis, who is acting as her temporary caddie, as she bids to expunge the memory of a missed two-footer, which cost her the LPGA Tour Championship crown last year.

She fired a four-under 68 on Saturday to take a commanding three-shot lead over compatriot Nelly Korda in the season-ender in Naples, Florida.

After making four of five birdies on the back nine at Tiburon Golf Club to put herself in position for her first win this year going into the final round, Thompson admitted to an ongoing struggle with body image issues, but having her brother on her bag was of great comfort.

"Everybody has imperfections," she said. "We're all not perfect, and we have to own it and love who you are," she told reporters.

"Golf is all about momentum. He's (Curtis) always cracking jokes out there. It's been a nice, relaxing week just having him on the bag and having all my family and friends out here supporting me."

A victory would extend Thompson's streak to six straight LPGA seasons with at least one win and her 16-under total of 200 took her clear of Korda, who had eight birdies in her 67.

Spain's Carlota Ciganda, who had three birdies without a bogey in her 69, was a further three shots back.

World No. 1 and defending champion Ariya Jutanugarn ended her day 10 shots adrift of Thompson, but the Thai is still in position to claim the US$1 million (S$1.36 million) bonus for winning the LPGA's Race to the CME Globe season-long points chase for the second time in three years.

Australian Minjee Lee, Canada's Brooke Henderson, Japanese Nasa Hataoka and South Korea's Park Sung-hyun are also in contention for the bonus.

The 22-year-old Ariya, whose three titles this year include her second Major at the US Women's Open, is already assured of claiming the Player of the Year honours and is closing in on the Vare Trophy for lowest scoring average this term.

AGENCE FRANCE-PRESSE