LANCASTER, Pa. (AP) -- Amy Yang rolled in four consecutive birdies in a round of 4-under 66 Friday for a three-stroke lead after two rounds of the U.S. Women's Open.
While the bulk of the field tried to solve the sloping greens at Lancaster Country Club, Yang charged into the lead on her inward nine with birdies on the 11th, 12th, 13th. She hit her approach to within a foot on No. 14 and punctuated the run. The 25-year-old South Korean was at 7-under 133.
"I just enjoy it out here," Yang said. "And I know the golf courses are very tough; I just enjoy the tough condition of the golf courses."
Stacy Lewis, last year's runner-up, and Japan's Shiho Oyama were tied for second at 4-under 136. Lewis birdied four of eight holes in the middle of her round, but bogeyed her last and settled for a 3-under 67.
Oyama had an opening 70 and was 2 over early in her second round before rallying. She made six birdies in a 12-hole stretch, including four on her second nine, on the way to a 4-under 66.
Yang has had her share of success on the LPGA Tour, earning a pair of victories since turning pro in 2006. But some of her finest golf has been played in the U.S. Open, where she has finished in the top 10 four times in the last five years.
She tied for fifth in 2010 U.S. Open, shared 10th place the following year and placed second in 2012. Last year at Pinehurst No. 2, she was third after 36 holes and first after 54 before closing with a 74 and finishing fourth.
She was paired with eventual winner Michelle Wie in the final round at Pinehurst and believes that experience can only help over the final two rounds.
Lewis' patience was tested early in the first round as she struggled with four bogeys and two birdies before breaking out of her funk. That carried over into the second round and she went on a tear that propelled her to near the top of the leaderboard - again - in the biggest event in women's golf.
"I just started playing golf, is really what it was," Lewis said, "I was thinking a lot those first 10, 11 holes, thinking a lot about my golf swing and just not playing. So I got to just playing golf ... and it's what you're seeing in the scores."
Marina Alex, part of a three-way tie for the lead after one round, carded a 1-over 71 and was next at 3-under 137.
Karrie Webb, also first round co-leader, had a 20-over 72 and was in a large group at 2-under 138. That group includes top-ranked and two-time champion Inbee Park (70), first-round co-leader Jane Park (72) and Morgan Pressel (70).
Inbee Park and Jane Park were two of the 55 players forced to finish their first rounds early Friday after play was suspended late Thursday when a powerful storm pounded Lancaster Country Club.
Jane Park, the 2004 U.S. Women's Amateur champion, was at the golf course early Friday and used a birdie and four pars to earn a share of the lead after one round.
Inbee Park, a two-time U.S. Open winner with titles in 2008 and 2013, played 22 holes Friday. She said her patience was tested by her poor putting.
"I hit probably every putt short, I missed it short," she said. "It's hard to think that you have to smash the putts at a U.S. Open. That's where putts are, really, really slow. It's a little bit disappointing. "
Wie rebounded from an opening 72 with a 2-under 68 and was seven shots off the lead.