South Korea's Park Sung-Hyun opened up a commanding three-shot lead at the season-ending LPGA Tour Championship on Friday, forging clear of the field after a front-nine birdie blitz.
The 24-year-old US Women's Open champion carded a seven-under-par 65 at the Tiburon Golf Club in Naples, Florida, to leave her at 12 under for the tournament heading into the weekend.
If Park manages to defend her lead she could scoop the Player of the Year honours as well as the LPGA money title and the $1 million bonus on offer for the Race to the CME Globe crown.
Park would also be likely to unseat China's Feng Shanshan as women's world number one with a victory.
The Korean rookie, who carded a 67 in the first round, got off to a steady start on Friday with four consecutive pars.
She then uncorked five straight birdies from the fifth hole onwards to put her at five under at the turn, 10 under overall.
A further birdie on 12 was followed by a spectacular eagle three on the par-five 17th, when she nailed a 30-foot putt. A bogey on the 18th, when she missed a five-foot par putt, was the only blemish.
"I didn't know I had made five in a row," Park said of her front nine birdie run. "I got behind in writing down my score and when I did and realized what I had done it felt good."
Park said she was not thinking about the possibility of a grandstand finale to her season. "I don't think about that other stuff," she said. "I don't feel quite as nervous as I thought I would. I can go into the weekend feeling a little more comfortable."
Park is being pursued by Germany's Caroline Masson, who is three shots back on nine under after a second-round 66. Masson is tied for second place with Australia's Sarah Jane Smith, who moved to nine under with a 69.
Three players are four shots off the lead tied for fourth -- Nelly Korda and Swedish duo Pernilla Lindberg and Madelene Sagstrom.
Two other players in the hunt for the Player of the Year honours -- Ryu So-Yeon and China's world number one Feng -- will need to produce something special this weekend to overhaul Park.
Both Ryu and Feng are 11 shots off the lead at one under.