Overnight co-leader Nancy Scranton managed a 3-under 69 on Friday and is tied for second place with Brandie Burton, who shot a 4-under 68 in round two. The pair is knotted at 10-under-par 134.
Nirapathpongporn, the 2003 U.S. Women's Amateur Champion, collected her first birdie at the par-5 second. She hit a pitching-wedge to 15 feet with her third shot and ran home the birdie putt.
At the par-5 fifth, Nirapathpongporn reached the putting surface with a 7-wood for her second. She knocked her approach to 15 feet, but two-putted for a birdie.
Nirapathpongporn made her move up the leaderboard around the turn. She hit an 8-iron to 8 feet to set up birdie at the ninth, then hit the same club inside a foot for a tap-in birdie at 10.
She parred her next six holes, but broke ahead of the field at the 17th. Nirapathpongporn hit a 52-degree-wedge to seven feet and drained the birdie putt to reach 11 under par.
'We're halfway and I look forward to playing the rest of the weekend,' said Nirapathpongporn. 'It's a place on the LPGA I haven't been, but every level of my golf career I have.'
Nirapathpongporn missed action earlier this season due to a freak eye injury. An exercise rubber band flew off a doorknob hit underneath her eye, which caused the inside of her eye to bleed. Nirapathpongporn missed three weeks, but used the down time to her advantage.
'I just learned a lot, that I have to be flexible and never take anything for granted,' said Nirapathpongporn. 'I think I've done just fine recovering. I'm back where I belong.'
Scranton began on the back nine Friday and recorded her first birdie at the 15th when her 12-footer found the bottom of the cup. She dropped a shot at 17 when she three-putted from 30 feet.
On the second nine, Scranton returned to the form that saw her shoot a 65 on Thursday. She took advantage of the early par-5s, with a pair of two-putt birdies at two and five. At the ninth, Scranton drained a 30-foot birdie putt to get within one of the lead.
'I played pretty well,' said Scranton, a three-time winner on the LPGA Tour, who has not visited the winner's circle since 2000. 'I wasn't quite as solid early today as I was yesterday. although I was hitting a lot of greens and fairways. Overall, I'm very pleased.'
Burton also began on the second nine at Corning and made her move with three consecutive birdies from the 14th, all from inside 12 feet. She added a birdie at the first from 20 feet, but trouble loomed.
At the fourth, Burton hit her tee shot long and left, She missed a 12-foot par save at that hole, then two-putted for birdie at the fifth to join Scranton in second.
'Actually, I played very steady today,' said Burton, whose winless streak dates back to 1998. 'I had quite a few opportunities, but didn't capitalize on them.'
Liselotte Neumann (69) and Hee-Won Han (70) are tied for sixth place at minus-8.
Stephanie Louden (69), Mhairi McKay (67), Stacy Prammanasudh (68), Audra Burks (68), Kris Tamulis (71) and first-round co-leader Meena Lee (72) are tied for eighth place at 7-under-par 137.
Defending champion Jimin Kang shot a one-under 71 on Friday and is tied for 50th place at minus-1.
The 36-hole cut fell at even-par 144 with 72 players advancing to weekend play.