Karrie Webb needs a low final round to win the Women's PGA Championship at Westchester Country Club in New York, despite finding some of her best form of the 2015 LPGA season.
Webb is tied-third through three rounds of the season's second major championship behind the world No. 2, Inbee Park of South Korea.
The 40-year-old Webb carded a third-round 72, one-under par, to be eight-under overall.
But Park took control of the event she has won in both of the past two years at different courses, firing a 66 in which she did not miss a single fairway and had just 27 putts.
The Korean, who will overtake Lydia Ko as world No. 1 if she wins tomorrow, is at 14-under par and leads by two shots from Sei-Young Kim.
"Obviously I've done something three times before,'' said Park. "I won three majors in a row before (in 2013). I'm just trying to give myself the confidence that I can do it, another three-time tomorrow. The way I've been playing, I've been really happy with ball-striking and today was the best putting day yet.''
Webb is six shots back along with Suzann Pettersen and Brooke Henderson, probably out of contention.
Meanwhile in the Fedex St Jude Classic on the United States PGA Tour, Matt Jones has made a run to a tie for fifth through three rounds after scores of 69-67-68. Jones, who is three shots back from the lead held by England's Greg Owen going into the final day, can pitch himself into next week's US Open if he wins the tournament.
The Sydneysider is currently No. 72 in the world; the top 60 on next week's rankings all have a right to play in the Open at Chambers Bay in Washington state.