She’s effectively won lotto six times in one week, but low-maintenance tennis superstar Ashleigh Barty only plans on splashing out on her niece and nephew following her historic pay day in China.

Australian sport’s new six-million-dollar girl promises fortune and fame won’t change her after squirrelling away the biggest cheque in tennis history with her WTA Finals success in Shenzhen.

Barty pocketed $6.4 million for crowning her triumphant season with a 6-4 6-3 victory over defending champion Elina Svitolina on Sunday night.

No player – not even Roger Federer, Rafael Nadal or Serena Williams – has ever received such riches from a single tournament.

But Barty declared “I’ve got everything that I need” before revealing her plans to spoil three-year-old niece Lucy and near-two-year-old nephew Oscar.

“Thankfully they can’t read but for Christmas they’re getting a new swing set, which they’re pretty excited about now that they’ve got the trampoline and swing set out the back,” the humble champion told AAP in Shenzhen.

“And I know Luce and Oscar are very keen to learn how to play tennis so I think that’s going to be pretty special to try and get a racquet in their hand. They already run around with a racquet, it’s amazing.

‘I’m not living an extravagant life’

“So, look, I mean the amount of zeros you have in the bank account doesn’t change how I’m going to spend my off-season and spend time with my family.

“Because that’s one of the biggest times that I miss throughout the year, is spending genuine time with them.

“It’s great that I can buy them things that they love but I live a pretty simple life. I’m not living an extravagant life.

“I’m pretty happy in my little house at home. I’ve got everything that I need. I’m pretty boring. I don’t really spend a lot on myself.”