Australia's world No.1 tennis superstar immediately apologised for her "innocent mistake" after forgetting her mask following a pre-Australian Open training session at Melbourne Park.

Barty was buying water melon when she ran into a Sky News reporter who took to Twitter with the "breaking news".

"I accidentally forgot to wear a mask in a supermarket (on Thursday) in Melbourne," Barty said.

"I apologised as soon as I realised my mistake.

"I understand we all need to do our bit to keep the community safe and I will be better next time."

Barty, the 2020 Young Australian of the Year, could be forgiven for her oversight, having spent the much of the past 10 months at home in Queensland, where coronavirus restrictions have been relatively low compared to the rest of the country.

The squeaky-clean 24-year-old was the highest-profile player in the world to opt out of a return to the tour during the pandemic last year.

Set to make her first on-court appearance since last February at next Friday's Adelaide exhibition event alongside Serena Williams, Simona Halep, Naomi Osaka and men's greats Rafael Nadal and Novak Djokovic, Barty cited health concerns for not playing during COVID-19.

But she can't wait to return to action.

"We are so lucky in Australia to have a home grand slam; the support of the Australian fans means the world to me and I always want to do well here,'' Barty said.

"I understand this year will be different in many respects but I hope I can do the local fans proud.

"The circumstances around this year's event are definitely challenging and I understand the frustration of all the players who have had to quarantine.

"But keeping Melburnians safe and making sure we put health first has to be the priority."

Australian Associated Press