Uncomfortable about travelling during the coronavirus pandemic and with her preparations hampered by COVID-19 restrictions in Australia, Barty announced her planned no-show at Roland Garros on Tuesday.

The bombshell call to end her season could also cruel the Queenslander's hopes of finishing as world No.1 for the second straight year.

Despite holding a significant lead atop the rankings after winning her eighth career title in Adelaide this year, then reaching the Australian Open and Doha semi-finals, Barty will come under threat from world No.2 Simona Halep - and potentially others.

But, as she did by skipping the US Open in New York, the 24-year-old is once again putting her wellbeing, and that of her tight-knit team, first.

"It has been a difficult decision to make but unfortunately I will not be competing in Europe this year," Barty said in a statement.

"Last year's French Open was the most special tournament of my career so this is not a decision I have made lightly.

"I wish the players and the French Federation all the best for a successful tournament.

"Thank you to my fans for your continued support. I can't wait to play for you again."

Australia's first women's world No.1 in almost half a century, Barty cited two reasons for her decision to bypass the claycourt slam in Paris, which starts on September 27.

"The first is the health risks that still exist with COVID," she said.

"The second is my preparation, which has not been ideal without my coach (Craig Tyzzer) being able to train with me due to the state border closures in Australia.

"It has been a challenging year for everyone and, although I am disappointed on a tennis front, the health and wellbeing of my family and my team will always be my priority.

"I now look forward to a long pre-season and the summer in Australia."

Barty has spent a total of 40 weeks as world No.1, the 12th-longest reign in history, having just eclipsed Amelie Mauresmo's 39-week stint at the summit.

But, depending on how Halep fares at Roland Garros and beyond, and how others including former world No.1 Naomi Osaka finish up in New York this week, Barty could relinquish her top-seeding status for her home slam in Melbourne.

Despite Victoria's ongoing battle with coronavirus, the 2021 Australian Open is still scheduled to go ahead as planned from January 18-31.

Australian Associated Press