Shiho Oyama fired a 4-under-par 66 on Friday to climb into a tie for second place after the second round of the U.S. Women's Open.
Oyama, the 2006 money winner on the Japanese tour, reeled off six birdies against a pair of bogeys at the par-70 Lancaster Country Club, finishing the day at 4-under 136.
The 38-year-old from Miyazaki Prefecture was tied for second place with American Stacy Lewis, three shots behind South Korean leader Amy Yang, who shot a 66.
"I hit the irons really well so I was able to create lots of birdie chances," said a delighted Oyama, who is playing in her first U.S. Women's Open in six years.
"I am pleased that I am able to be back here again. This is the best."
Oyama bogeyed her opening hole after teeing off on the 10th and dropped another stroke at the 13th.
But she rebounded with back-to-back birdies from the 14th and never looked back, picking up for more shots on a bogey-free outward journey.
American Marina Alex carded a 71 and was a further stroke back, while Rumi Yoshiba shot a 68 and was tied for fifth at 2 under with world No. 1 Park In-bee of South Korea and four others.
"I did well," said Yoshiba. "My tee shots were good so it made it easy to create chances from the fairway."
Also for Japan, Ai Suzuki shot a 71 and had a share of 20th at 1 over alongside compatriots Lala Anai and Ayako Uehara.
Erika Kikuchi was in 32nd at 2 over and Sakura Yokomine and Haruka Morita made the weekend rounds after closing in 54th place.
Fourteen-year-old amateur Suzuka Yamaguchi, Mika Miyazato and Misuzu Narita all missed the cut.