Canadian coach John Herdman acknowledged that some of his players made some nervy, nearly costly mistakes during the early stages of Saturday's 1-0 win over China in the tournament opener. But not Buchanan.
"There's no jitters there," Herdman said admiringly. "That's a kid 19 years of age who just stepped and played like THE best centre back in the world. Look, I'm going to give her that label. That was as good a performance I've seen under that sort of pressure from a centre back."
Canada needed a strong showing from Buchanan on the weekend. Centre back partner Lauren Sesselmann had an erratic outing.
Buchanan emerged from the China game with an ankle contusion but says she is not worried about the knock.
And she reports the Canadian team, with a win under its belt, is "in a great space right now."
Buchanan certainly looks right at home. Physical and fearless, she is extremely hard to beat one-on-one. Plus she has the strength and athleticism to recover if an attacker gets a foot up on her.
Her battles with veteran American striker Abby Wambach, who is at the other end of her career, have been relatively few but memorable with Herdman gleefully giving the edge to his player.
"I'm not frightened to say it. She's the Sinclair of defenders," Herdman said in May 2014 after Buchanan and Wambach faced off in a 1-1 draw in Winnipeg. "She's that good."
"Abby Wambach's scored 200-plus goals in her career. And Kadeisha Buchanan was the better player tonight," he added, rubbing salt in the wound.
A measure of Buchanan's importance to the Canadian team is that she has won 36 caps already. Buchanan was 17 when she made her senior debut against China in January 2013.
On Thursday, she will lead the Canadian defence against a New Zealand side with its back against the wall after a 1-0 loss to the Netherlands.
Buchanan says she is focused but relaxed on the pitch "because I know the hard work that I put in, it'll just flow right through me."
Away from the pitch, Buchanan is also chill personified. It wasn't always like that around teammates like captain Christine Sinclair.
"I'm not nervous anymore. I used to be super-nervous around Sinclair ... I was a huge fans of hers."
Growing up, Buchanan played striker but switched to midfield and then defender at the U-15, U-16 level.
A sophomore at West Virginia, she took the spring semester off to concentrate on Canada. She will return to school in the fall.
"I love it out there. The fans are great. The people are great out there."
Buchanan's mother had seven daughters, with Kadeisha the youngest. Two others played soccer and Buchanan says they made her "tougher, faster, stronger, smarter."
Family is key. She has the word tattooed on her forearm. "I keep them at arm's reach," she said.
While she has relatives in Edmonton, family and friends will be gathering in numbers in Montreal next Monday for the final Group A game against the Netherlands.
Buchanan, a Barcelona fan who grew up a fan of Ronaldinho, estimates she had more than 50 supporters in the BMO Field stands in June 2013 when she played in her native Toronto in a 3-0 loss to the U.S.
Buchanan and childhood friend Ashley Lawrence, a 19-year-old midfielder, join 17-year-old midfielder Jessie Fleming as the youngest members of Canada's World Cup squad.
New Zealand, the team Herdman left to coach Canada, is ranked No 17 in the world, compared to No. 8 for Canada.
Follow @NeilMDavidson on Twitter