Lydia Ko has produced a birdie blitz to storm into the lead at the season-opening LPGA Tour event in Florida.
The 17-year-old New Zealander made her charge on day three of the $US1.5 million ($A1.93 million) tournament at Ocala by firing a seven-under 65.
Her score took her to 14-under and gave her a one-shot advantage over overnight leader Ha Na Jang of South Korea.
The final round promises to be a tight one, with just five shots covering the top seven players.
Ko, who this week has been wearing contact lenses rather than her trademark glasses, began her round in a tie for fourth, five shots off the pace.
She had four birdies in the first seven holes to get to within one stroke of the lead, but faltered with bogies on the 10th and 11th.
The world No.2 then embarked on a run of five consecutive birdies to sit alone at the top, before closing with pars on her last two holes.
Jang, a tour rookie who had to qualify for the tournament because the event isn't a full-field one, carded a 71 to be one stroke ahead of compatriot Na Yeon Choi, who had a 66.
Ko's form this week has followed on from an impressive debut professional season, which included three wins to take her tally of LPGA victories to five.
In all, she had 15 top-10 finishes in 2014 and pocketed more than $US2m in prize-money.
If Ko wins this weekend, she will become the world No.1 irrespective of how others fare, overtaking South Korea's Inbee Park and becoming the youngest player to hold that status.
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