While Barty has been World No.1 since winning the French Open in 2019, many critics say she wouldn't have held onto the top spot if the WTA hadn't frozen the rankings during the COVID-19 pandemic.
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Barty was able to stay at home in Australia for the majority of 2020 and not worry about losing the No.1 ranking because of the revamped WTA system.
Many believe Naomi Osaka is the true World No.1, with the Japanese star winning her fourth grand slam title at the Australian Open in February.
Barty only has one grand slam title to Osaka's four, with many pointing to the Aussie's inability to perform on the big stages of the US Open and Australian Open as proof that she's a pretender.
But in winning the title in Stuttgart on Sunday, Barty silenced her critics and showed she's the true No.1.
She beat the World No.5, 7 and 9 en route to the title, taking down Elina Svitolina, Aryna Sabalenka and Karolina Pliskova.
She's now won 10 consecutive matches against top-10 opponents and 17 of her last 20.
Her Stuttgart title sends her to the top of the WTA's 'Race to Shenzhen' (the year-end WTA Finals) - the order of merit system that identifies the year's top female player.
Barty's triumph also extends her lead in the rankings over World No.2 Osaka - 9655 points compared to Osaka's 7800.
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It was her first European tournament on clay since triumphing in the 2019 French Open and she looked in the sort of form to regain the trophy that she decided not to defend last year.
Her brilliant three-set victory over Sabalenka in the final was the sign of a champion who, as Barty conceded herself, is now taking her game "to a kind of a new level."
After picking up her third title of the year after also winning the Yarra Valley Classic and Miami Open, the 25-year-old birthday girl explained that it was because she felt she was now playing "tennis without consequence".
"For me, it's a level of freedom," said Barty.
"If I miss or make a mistake, it's okay. It's not going to be the end of the world if I make a few errors. It's just playing without consequence and not focusing on the result as such."
The World No.1 says her new approach stems from work she's done with mindset coach Ben Crowe.
"There are many things we've worked on. It's something I've always tried to do and always remind myself of what it felt like to play when I was a little kid.
"It didn't matter what happened, it was just about the playing.
"That's a massive part of who I am now. I want to go out there and have fun because ultimately it's what I love to do and results weren't my love for the sport or how I feel about the sports.
"It's just trying to find the right way in the right spirit."
WTA Race to Shenzhen
1. Ash Barty (Australia) — 2471 points
2. Naomi Osaka (Japan) — 2400
3. Garbine Muguruza (Spain) — 1980
4. Jennifer Brady (USA) — 1498
5. Aryna Sabalenka (Belarus) — 1422
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