On Tuesday, Gold Coast's former Australian No.1 sensationally knocked out No.5 seed Jessica Pegula with the win of her career, cheered on Roland Garros's famed greenhouse arena, Court Simonne Mathieu, by her close 'Paris family'.
That's the family of her mum's best friend, with whom Birrell stays whenever she's in the French capital, and she swears it's just the added edge she needs as she seeks to make the third round in a slam for the first time by defeating Ukraine's Oleksandra Oliynykova on Thursday.
"This is definitely a piece of home for me," explained the 28-year-old.
"As Aussies, we're just on the road all the time. So to have somewhere where I can see people I love, leave some stuff in Europe, make my bags a little bit lighter when travelling around to tournaments and get a home-cooked meal, it really helps.
"I also know the area that they live really well now. It's so familiar.
"My parents, they're Aussies who lived in Germany for quite a while, where I was born (in Dusseldorf). My mom met a lovely French lady, and they've been best friends since their 20s when they met in Germany.
"So each time I come to Paris, I stay with them, and they've also come to Australia throughout my childhood. Their girls are similar age to me and my brother and are some of our closest family friends."
She'd wanted to get a first win for them on her fifth visit to Roland Garros. "So this was a pretty cool moment for me to win and see them in the stands watching."
Birrell's tale has been one of real resilience, having endured moments when she feared an elbow injury could end her career, and so is the story of her next Ukrainian opponent Oliynykova.
With her fake facial star tattoos and her creative on-court game, she was an instant hit at the Australian Open, giving defending champion Madison Keys a scare in the opening round.
And after winning her first grand slam match in Paris on Tuesday against Russian qualifier Elena Pridankina, she handed her national flag on court to her father Denis, who's on leave from the Ukrainian army.
Holding up a phone at her press conference showing the bombed out courts she once played on in Kyiv, she launched a withering attack on those Russian players she believes are part of propaganda machine.
And asked about the prospect that Russian players might again soon be playing under their national flags again, she said: "This flag is a symbol of terror, something that the Russian soldiers are flying after they are destroying the city completely.
"The cities where they're coming with only one intention: to destroy, to kill, to rape, to steal. These symbols are horrible. This is something absolutely unacceptable, and for Ukrainians, it is very traumatising.
"In the modern context, it's the same thing like using, I don't know, a swastika. Let's go on court with a swastika. The fact that now this is under any discussion, it's horrible."
AUSTRALIANS IN ACTION ON DAY FIVE OF THE FRENCH OPEN (number denotes seeding)
Men's singles second round
Adam Walton v Zachary Svajda (USA)
Women's singles second round
Daria Kasatkina v Susan Bandecchi (SUI)
Kimberly Birrell v Oleksandra Oliynykova (UKR)
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