Cristie Kerr made a 55-foot par-saving putt to grab a share of the lead after 54 holes of the Kia Classic in Carlsbad, California.
The American is tied with compatriot Lizette Salas at 10 under par after posting a two-under 70 in round three.
At the last, Kerr holed out from the edge of the green after taking a penalty drop because her approach to the 18th green had landed in water.
Kerr admitted: "Obviously, it was the worst shot I could have hit and then it was the best shot I could have hit.
"It was pretty amazing. It is really one of those moments that you just remember for a lifetime. I was just trying to get it close. Usually that's when those go in."
Salas, who carded a 69, has posted just a single bogey in 54 holes this week.
She said: "I'm just really trying to capitalise on the par fives and just staying patient. That's really my key this week is to stay patient.
"I felt like I left some putts out there but I'm still hitting great shots and giving myself opportunities for birdies."
Swede Anna Nordqvist is one of four players tied for third place - two shots behind the co-leaders.
Nordqvist fired a 67 that yielded four straight birdies on the front nine and just one bogey.
She added: "I think the back nine is playing a little tougher but I hung tough and made a silly mistake on 16. But other than that, I'm really happy with my round."