Lorena Ochoa, the No. 1 player in women's golf seeking her first major, was poised to join Kerr atop the leaderboard until she got too aggressive with a 30-foot birdie putt on the 18th hole and wound up with a three-putt bogey for a 68.
Kerr, at 4-under 209, was to start the final round in the last group, one shot ahead of Ochoa and Kraft Nabisco champion Morgan Pressel, who saved par with a 25-foot putt for a 69.
A tournament that has lacked rhythm because of so many thunderstorm delays finally took shape Sunday morning under a blue sky at Pine Needles.
On a tour dominated by players who skipped college or didn't spend much time there, Kerr was among the pioneers. She turned pro 11 years ago upon high school graduation and has compiled nine victories, although the 29-year-old from Miami has been overlooked in recent years with the arrival of young Americans such as Pressel, Paula Creamer and Brittany Lincicome.
Ji-Yai Shin, a 19-year-old from South Korea, left Pine Needles at 5 under through 10 holes on Saturday evening, but bogeyed the first two holes of the morning before finishing with six straight pars for a 71. She also was at 210 with Ochoa and Pressel.
Angela Park, the 36-hole leader, never made another birdie after the first hole and shot 74 to finish at 2-under 211. They were the only five players under par.
Ochoa played 29 holes Saturday because of the delays, including the final 22 holes in 7 under par. Determined as ever to validate her No. 1 ranking, the 25-year-old Mexican hit an 8-iron to 12 feet on the 12th hole for her first shot of the day and holed the birdie putt, which put her in the lead for the first time all week.
But she missed three putts inside 7 feet over the last five holes, and it kept her from building a big lead.
Ochoa hit hybrid into a bunker on the 14th, blasted out to 7 feet and missed the par putt. She got a bad break on the par-5 15th when her 3-wood took a hard hop to the left, and instead of the ball going into the bunker, it was gobbled up by thick grass on the back. She did well to chip to 6 feet, but again missed the putt.
Then came the final hole, when her birdie putt raced 6 feet by the hole and she missed it coming back.
Still, her spirits were high.
Ochoa blew a chance to win the Women's Open in 2005 at Cherry Hills when she was on the verge of posting a score an hour before the leaders finished, but hooked her tee shot into the water and took 8 on the last hole. She was in the lead in the third round of the Kraft Nabisco until taking a quadruple-bogey 7 on the 17th hole, and never recovered.
This might be her best chance, although it figured to be a tough test.
Pressel was runner-up at Cherry Hills as a 17-year-old amateur, and she won the Kraft Nabisco at age 18 by making no worse than par over the final 24 holes, becoming the youngest major champion in LPGA Tour history.
Defending champion Annika Sorenstam's hopes of joining Mickey Wright and Betsy Rawls as the only four-time champions of this event likely ended with a 72, leaving her 10 shots behind.