Yamahita rebounded from a bogey on the par-3 17th with a birdie on the par-4 18th to get to 19-under 191 at Royal Mayfair, the tree-lined layout (and mosquito hot spot after record summer rain), tucked in a bend in the North Saskatchewan River.

The 25-year-old, one of professional golf's shortest players at 491cm (4-foot-11), won the Meijer LPGA Classic in June in Michigan after taking the Women's Open Championship and Maybank Championship last season as the rookie of the year.

A stroke ahead Thursday after opening with a course-record 62, Yamashita had a 64 on Friday afternoon to open a five-shot lead.

"I like this course," Yamashita said through a translator. "I'm feeling so good out there."

American Gina Kim (64) and Japan's Yuri Yoshida (66) were tied for second at 13-under, a shot ahead of Jennifer Kupcho (64) and two ahead of Somi Lee (65).

Aphrodite Deng, the 16-year-old amateur who won the 2025 US Girls' Junior, was the top Canadian, shooting 63 to get to 10-under and be tied for sixth.

"I wasn't really counting how low I was shooting," Deng said. "I was just trying to play as best as I can."

Cassie Porter (69) and Karis Davidson (70) were the leading Australians, tied 30th at four-under, with Robyn Choi (70) and Grace Kim (71) a further shot back. 

Canadian star Brooke Henderson, the 2018 and 2025 champion, was seven-under after a 68.

"I hit 16 greens and gave myself a lot of good looks, so it's disappointing to only shoot two-under," said Henderson.

Top-ranked Nelly Korda shot a 69 to get to four-under. Lydia Ko, the 2013 winner at Royal Mayfair as an amateur, was two-under after a 69.