Candie Kung found her groove at the halfway stage of the Canadian Women`s Open, but world number two Lydia Ko and first-round leader Karine Icher are also in the hunt.
The 34-year-old Kung birdied four of her final six holes to fire a bogey-free eight-under 64 to reach 11-under 133 and seize a two-shot lead over Kiwi Ko and France`s Icher on Friday.
"I just went out there, played one shot at a time, and I knew that I was putting pretty good," the halfway leader Kung said.
"I missed a few out there from about ten feet. I was hitting them pretty close all day. And then made some key putts coming in."
Ko, who was a 15-year-old amateur when she won at Vancouver Golf Club in 2012, shot a four-under 68 to reach 135 along with Icher, who fired a 70.
Taiwan`s Kung, who is seeking her first win on the LPGA Tour in almost seven years, is coming off a tie for second place at last week`s Portland Classic.
She won three events in 2003 but has only one win since then, in 2008 in South Korea.
Kung failed to crack the top 30 in any of the first four major tournaments of 2015, and she hasn`t had a top-10 finish in a major since finishing as runner-up in the 2009 US Women`s Open.
Kung finished eight shots back of Portland Classic winner Brooke Henderson of Canada but said it gave her confidence heading to Vancouver.
"I`ve been playing well," Kung said. "Just the putter has to go and so far it`s been going pretty good the last six tournament days."
Kung, who began her second round on the 10th tee, got off to a dazzling start with back-to-back birdies and then put a stamp on her hot start with an eagle at the par-five 13th.
She added four birdies on her second nine, including three in a row from number six to the par-four number eight.
Ko also registered a bogey-free round, making two birdies on the front nine and two more on the back nine.
Icher recorded her first two bogeys of the tournament but also carded four birdies.
China`s Xi Yulin moved into contention with the second-best round of the day, a 66, to take sole possession of fourth place at 136.
Stacy Lewis (70) and Spain`s Azahara Munoz (67) are tied for fifth at 138.
South Korea`s Kim Hyo-Joo is in seventh place at 139 after firing a 68.
Seven players, including top-ranked Park In-Bee, are tied for eighth at 140.