Australian women's number one Ajla Tomljanović has been forced out of the Australian Open with a lingering knee injury.

Tomljanović previously pulled out of the United Cup due to the injury, and confirmed on Saturday she had been unable to recover in time to contest her home grand slam which starts on Monday.

The 29-year-old's withdrawal is a hammer blow to Australia's hopes of a local woman going deep into the tournament.

A year after now-retired Ash Barty claimed a breakthrough Australian Open title triumph, Australia has only five women, none inside the top 100, left in the draw.

Tomljanović posted the words "I'm sorry" on Twitter, with a longer statement confirming her withdrawal attached to the post.

"It absolutely pains me to have to write this message but unfortunately I won't be able to compete at this year's Australian Open," she wrote.

"I've done absolutely everything in my power to get healthy but just ran out of time to heal and be 100 per cent ready to compete at a high level.

"It's been a very tough decision to make but I have to listen to my body.

"It's no secret that this is my favourite place to play so it hurts to miss out on a great opportunity to play in front of my home crowd and to be surrounded by the incredible love and atmosphere."

Australian Open tournament director Craig Tiley said Tomljanović's withdrawal was "unfortunate".

"She will go and re-group, do some rehab and try and get herself healthy," he told ABC Sport.

In 2022 Tomljanović became the first Australian woman since former world number one Evonne Goolagong Cawley in 1979 to reach the quarterfinals at both Wimbledon and the US Open, where she famously ended Serena Williams' career, in a calendar year.

She was in line for a precious first-time grand slam seeding at her home major until the injury ruined her leading, and resulted in her ranking dropping to number 35.

Her unseeded status had delivered her a difficult draw.

The Australian was due to play Argentina's world number 192 Nadia Podoroska first-up, but she then faced either Sofia Kenin or Victoria Azarenka in the second round.

With Barty retired, and regular campaigner Daria Saville ruled out in September after suffering a serious knee injury, Tomljanović had been comfortably Australia's best hope.

The remaining Australians are Jaimee Fourlis, Olivia Gadecki, Storm Hunter and Talia Gibson, and late addition Kimberly Birrell, who earned a spot following the withdrawal of Venus Williams, who had a wildcard.

Gadecki, who is being mentored on-site by Barty, and West Australian teen Gibson are making their Open debuts.

AAP