Inbee Park led entering the third round of the U.S. Women's Open on Saturday, and she was the only player to break par in that round.
Park birdied the 18th for a 1-under 71 at Sebonack Golf Club. She ended 54 holes at 10-under-par 206.
Park has won the season's first two major championships, and has five victories in all this year. If she can hang on and win, Park would become the second player in LPGA Tour history to win the season's first three majors.
I.K. Kim posted a 1-over 73 to end three rounds at minus-6. Kim, who lost in a playoff at the Kraft Nabisco last year, is looking for her first major championship.
Kim does own one USGA title. She defeated Park, 5 & 4, in the finals of the 2005 U.S. Girls Junior.
Jodi Ewart Shadoff carded a 2-over 74 and finished three rounds alone in third at 3-under 213. Angela Stanford (74) and 2011 champion So Yeon Ryu (73) are the final two players in red figures at minus-1.
The second round was completed earlier Saturday after being suspended due to fog on Friday.
Park, Kim and Ewart Shadoff were the final group on Saturday as players went out in threesomes off the first and 10th tees. Park and Ewart Shadoff both had eight pars and a birdie on the front nine.
Ewart Shadoff birdied the eighth from 15 feet out to move within three at minus-6, but Park responded with a 4-foot birdie putt at the ninth to make the turn with a 4-stroke lead.
Kim had two bogeys, a double-bogey and three birdies on the front nine as she made the turn at minus-5. Ewart Shadoff bogeyed the 10th and 12th to slide to 4-under, where Kim joined her with a bogey on the 11th.
They didn't lose any ground, though, as Park struggled early on the back nine. She failed to get up and down at the 11th, then dumped her tee shot into a bunker at the par-3 12th.
Park walked off the 12th with another bogey. She tried to run a chip around a bunker on the par-5 13th, but she hit the shot heavy and the ball rolled into the sand.
The 2008 champion blasted her fourth within 10 feet, but was unable to covert the par effort. The three straight bogeys dropped Park to 7-under, where she was three clear of her playing partners.
"I just hit a couple of shots that I didn't want to hit. I just missed it in the wrong spots. The 11th and 12th weren't that bad of bogeys, but the 13th was a disappointing bogey. After that, I started hitting some good shots and finished under par," Park said.
At the par-4 14th, which ended as the seventh hardest hole of the day, all three made birdie. Park's was the most unlikely and came first, as she drained a 30-footer that was sharply downhill.
Ewart Shadoff and Kim responded as the both made birdie from just over 10 feet out. That was the turning point for the leader.
Park birdied the par-5 15th to push her lead back to four. After a pair of pars, Park converted an 8-footer for birdie at the last to finish four clear of Kim.
"I had a lot of long irons into the greens. It was just a tough day, but I think I battled it really good out there," Park said. "I had my tough times in the middle, but ended of finishing good."
Kim 2-putted for birdie at the last to stay within four.
Ewart Shadoff bogeyed the 16th and 17th to slide seven behind Park.
NOTES: Park owns the 54-hole for the seventh time in her LPGA Tour career ... She has gone on to win the last two and three of the previous six overall ... If she wins, Park would claim the fourth major championship of her career ... Jessica Korda fired her caddie in the middle of the round, and her boyfriend caddied for her on the back nine. She opened with a 5-over 40, and came home in 1-under 36 for a 76 ... After Friday's suspension due to fog, the cut fell at 6-over 150, with 68 players making it to the final two rounds.