Women’s world No. 1 Ashleigh Barty pulled out from the maiden edition of the Billie Jean King Cup in Prague next month, officials said Tuesday.

The Wimbledon champion, who returned to Australia after a third-round exit at the U.S. Open in September, led her country to the final of the last completed edition of the Fed Cup in 2019.

The women's team tournament was canceled because of the global health crisis last year and subsequently renamed in honor of American trailblazer King. Former U.S. Open champion Sam Stosur, another Fed Cup stalwart, will also miss the Nov. 1-6 finals

Tennis Australia gave no reason for Barty's absence, simply saying world number 47 Ajla Tomljanovic would lead Australia's five-player team in the Czech Republic.

"Ajla has had an incredible year and this is a great opportunity for her to lead the team," captain Alicia Molik said in a news release, according to Reuters. "Storm and Astra are both tremendous team players and it's exciting to welcome Ellen and Olivia to the team for the first time."

Australia won the Fed Cup seven times, with the last title coming in 1971.

The decision raises doubts about 25-year-old Barty's participation in the rest of the 2021 season, including her defense of the WTA Finals title she won in 2019 before last year's version was canceled due to the COVID-19 pandemic.

Her coach, Craig Tyzzer, said last month that Barty might not defend the WTA Finals title she won in Shenzhen in 2019 when the elite season-ending competition returns in Guadalajara, Mexico from Nov. 10-17.

Barty had a stellar start to the year, winning five titles including Wimbledon, which gave her a second Grand Slam to add to her 2019 French Open crown.

But she has not played since suffering a shock third-round loss to American Shelby Rogers at the U.S. Open in early September, when she said the year had been a "rollercoaster."

Her best performance at her home Grand Slam is a semifinal appearance in 2020.

If Barty does travel to Mexico for the season-ending WTA Finals, Australia's strict border controls mean she would face two weeks quarantine upon returning home, potentially disrupting her training.

"Ash has qualified for the WTA Finals and will make her decision on whether to play Mexico closer to the event," Barty's manager Nikki Mathias told Reuters.