The 26-year-old Ji is no stranger to Locust Hill, having captured her first career LPGA Tour victory here in the 2008 Wegmans LPGA, when the Rochester stop was a regular tour event.
She had eight pars and a bogey on the front side and a bogey at 10 dropped her three shots behind the leaders. She rallied on the back side with birdies at Nos. 13, 15, and 16 but couldn't keep it going over the final two holes.
Even with the gallery rooting hard, Creamer, a crowd favorite, was dreading this tournament because of the death in March of her 94-year-old grandfather, Tom, her biggest fan. She dropped on shot on the front nine and managed only one birdie on the back side.
The final twosome of Webb and Ji both hit great drives to start, and when Ji hit her second shot inside 8 feet, Webb duplicated it as a fan shouted "Game On!"
Ji missed, but Webb sank hers to tie for the lead at 4 under with Ji and Pettersen, who birdied the second and third holes.
Webb faltered with bogey at No. 3 as Pettersen continued a front-nine surge with a long birdie putt at the par-3 fifth hole. The long-hitting Norwegian star clenched her right fist and pulled her arm back in celebration as she gained sole possession of the lead at 5 under.
Feng had two birdies over her first six holes to move one shot behind and nearly took the outright lead at No. 8. But her eagle try slid just past the hole and she settled for a tie with Ji and Pettersen.
Pettersen won the 2007 LPGA Championship at Bulle Rock, beating Webb by one shot, but has had not-so-great moments in major play, having been a runner-up three times at Kraft Nabisco. The most painful was in 2007 when she lost to Morgan Pressel, blowing a four-shot lead over the final holes. She was solid on this day at the start and regained the lead with a birdie at No. 8, making the turn at 5 under.
A birdie by Feng at No. 12 moved her into a tie with Pettersen and the little-known Piller, who had only one top-10 finish since her rookie year two years ago.
Piller started the day at 1 over, five shots off the lead, but quickly made her way up the leaderboard with four birdies on the front side. Birdies at Nos. 11, 14 and 16 made her 9 under through a 19-hole stretch and moved her into a tie for the lead at 5 under.
But Piller found trouble at par-5 17th, which she eagled Saturday to begin her steady rise. She drove under a tree into the thick rough and her punch shot out clipped some leaves and she dropped two shots when her short bogey putt slid just past the cup.
Pettersen found rough on two straight shots at No. 13, chipped well past the pin and settled for bogey to fall one shot behind Feng. Pettersen drove the rough again at the 14th hole and again made bogey to fall two shots behind and never recovered.
Webb birdied No. 11 to reach 4 under again but gave it right back on the next hole when she drove into the rough and couldn't salvage par. Webb birdied Nos. 16 and 17, but like Ji her rush came too late.
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