LANCASTER, 11 Jul 2015 (AFP) - Yang finished on eight-under 202 at Lancaster Country Club, one stroke off the 54-hole tournament record set by American Juli Inkster in 1999. Yang and playing partner Lewis birdied three of the first six holes but struggled on the greens.
"I had a tough time getting the right speed on the green, but I've hit the ball great this week. I'll take positives from there," Yang said. "My coach and I, we have practised hard this week. I believe I can do well."
Yang, who shared the 54-hole lead last year at Pinehurst only to lose the US Women's Open to Michelle Wie, hopes to become the event's sixth South Korean winner in eight years.
US veteran Lewis was second on 205 after a 69 with South Korean Chun In-Gee third on 206 and Japan's Shiho Oyama fourth, another stroke adrift. No player has ever rallied from more than five shots down in the last round to win the US Women's Open.
"I need to hit a few more shots. Amy didn't give me anything out there," Lewis said. "A low number is out there. You have got to make some putts early."
South Korean Chella Choi, still seeking her first LPGA victory, fired the lowest third-round score in US Women's Open history, a 64, to join a pack in fifth at 208 that includes defending champion Wie and Koreans Lee Mi-Hyang and Park In-Bee, the world number one.
Choi made six birdies on the front side for a 29, the lowest nine-hole score in US Women's Open history, but missed a 3-foot par putt at 18 to match the tournament's record-low round of 63 by Sweden's Helen Alfredsson in 1994.
"I made birdie a lot, so my putting was good," Choi said. "I think my shot is really good always, but before tournament I changed my putter so I have confidence."
Yang followed an opening birdie with a bogey at the second. She bounced back with birdies at the fourth and par-3 sixth but took another bogey at the par-3 eighth. She birdied the par-5 13th but gave back a shot with a bogey at 14.
"I started with a good birdie but the putting was a little shaky. Pins were tricky. I had trouble," Yang said.
Lewis opened with a bogey but responded with birdies at the second, fourth and sixth before a bogey at eight. Lewis birdied the 14th but made a bogey at the par-3 17th.
"We were making putts on top of each other on the front. It was really cool," Lewis said. "I kept looking at the leaderboard expecting someone else to come up there but no one did."
Choi's nine birdies were the most in a US Women's Open round since Canada's Lori Kane had nine in the second round in 1999.
Five US Women's Open players previously had shot 30 over nine holes, most recently Jodi Ewart Shadoff in her first nine holes in 2013, but none had gone as low as Choi, who missed Alfredsson's 63 with a last-hole lip out.
Wie limped at times over the hilly layout but said she still figures she has a chance to become only the eighth back-to-back winner.
"It's definitely a little painful, but I'm good to go tomorrow," Wie said. "I've put myself in position where I have a chance."
Leading scores on Saturday after the third round of the US Women's Open (par-70, USA unless noted):
202 - Amy Yang (KOR) 67-66-69
205 - Stacy Lewis 69-67-69
206 - Chun In-Gee (KOR) 68-70-68
207 - Shiho Oyama (JPN) 70-66-71
208 - Chella Choi (KOR) 71-73-64, Michelle Wie 72-68-68, Lee Mi-Hyang (KOR) 68-72-68, Park In-Bee (KOR) 68-70-70
209 - Min Lee 71-68-70, Morgan Pressel 68-70-71, Jane Park 66-72-71
210 - Kris Tamulis 72-69-69, Ryann O'Toole 71-70-69, Ai Suzuki (JPN) 70-71-69, Ryu So-Yeon (KOR) 72-68-70, Pernilla Lindberg (SWE) 70-70-70, Rumi Yoshiba (JPN) 70-68-72
211 - Sakura Yokomine (JPN) 71-73-67, Lexi Thompson 71-72-68, Brooke Henderson 70-73-68, Sydnee Michaels 68-74-69, Jenny Shin (KOR) 74-68-69, Lydia Ko (NZL) 70-72-69, Lee Jung-Min (KOR) 70-71-70, Choi Na-Yeon (KOR) 67-74-70, Karrie Webb (AUS) 66-72-73, Marina Alex 66-71-74