WATERLOO, July 13, 2013 (AFP) - Matthew, ranked 13th in the world, had a 36-hole total of 15-under 127 for a three-stroke lead over American Angela Stanford, who started the day tied with Matthew for the lead.
Stanford carded five birdies with one bogey in her four-under 67 which put her on 12-under 130.
World number one Park In-Bee, who won her third major title of 2013 at the US Women's Open a fortnight ago, celebrated her 25th birthday by shooting a four-under 67 that left her five shots off the lead.
Matthew kick-started her round with an eagle at the Grey Silo course's par-five fifth, where she rolled in a 25-foot putt.
She added a birdie at the next hole and nabbed another birdie at the eighth to make the turn in 12-under.
"I played really well again, you know, gave myself a lot of chances," Matthew said. "It feels really good. I've holed a lot of putts. I've given myself a lot of chances, so I wouldn't say I've really holed many super long ones, but every time I give myself a chance, I'm kind of taking advantage of it."
Matthew added birdies at 11 and 16 before capping her round with a four-foot birdie putt at the last.
"When you're holing putts, it all seems quite easy," she said.
Stanford was pleased with her day's work, saying she was hitting the ball well.
"Ball striking for sure, giving myself some chances," Stanford said of her strengths. "I've been hitting it really well this week and I know what's going on in my golf swing and swing thoughts are good. So any time I'm feeling this way, I can't wait to try to make the putts."
Five players were tied for third on 11-under 131, including two-time LPGA winner Anna Nordqvist of Sweden, 2011 US Solheim Cup team member Ryann O'Toole, Spain's Belen Mozo and South Koreans Meena Lee and Chella Choi.
Park was one stroke back on 132, still within striking distance of a fourth LPGA victory in as many starts. She opened her round on the back nine and when she made the turn at 18 spectators in the grandstand at the green sang "Happy Birthday" to her.
"I've never had that many people wishing me Happy Birthday ever before," Park said. "I'll remember my 25th birthday forever."
Three players -- O'Toole, Nicole Hage and Momoko Ueda -- punched their tickets to next month's Women's British Open at St. Andrews based on their 36-hole scores.
Two more players this week will earn spots in the fourth major championship of the season, based on 54-hole scores.
Leading second-round scores here on Friday in the Manulife Financial LPGA Classic (USA unless noted,a-denotes amateur, par-71):
127 - Catriona Matthew (SCO) 63-64 127
130 - Angela Stanford 63-67
131 - Anna Nordqvist (SWE) 67-64, Ryann O'Toole 66-65, Chella Choi (KOR) 66-65, Belen Mozo (ESP) 65-66, Meena Lee (KOR) 65-66
132 - Suzann Pettersen (NOR) 68-64, Austin Ernst 68-64, Park In-Bee (KOR) 65-67, Park Hee-Young (KOR) 65-67
133 - Karine Icher (FRA) 67-66, Amy Yang (KOR) 66-67
134 - Jessica Korda 68-66, I.K. Kim (KOR) 68-66, Sandra Gal (GER) 68-66, Nicole Hage 67-67, Paola Moreno (COL) 67-67
135 - Mina Harigae 71-64, Stacy Lewis 68-67, Yoo Sun-Young (KOR) 68-67, Momoko Ueda (JPN) 67-68, Jennifer Johnson 67-68
136 - Felicity Johnson (ENG) 71-65, Kris Tamulis 71-65, Christina Kim 71-65, a-Brooke Henderson 70-66, Dewi Claire Schreefel (NED) 69-67, Michelle Wie 69-67, Jacqui Concolino 69-67, Kathleen Ekey 68-68, Lee Jee-Young (KOR) 68-68, Candie Kung (TPE) 68-68, Oh Ji-Young (KOR) 66-70, Jenny Shin (KOR) 66-70