World tennis No.1 Rafael Nadal is in doubt for the Australian Open pulling out of lead-up tournaments in Brisbane and Sydney.

Nadal hasn’t played since losing to David Goffin at the World Tour Finals in London in mid-November, when Nadal pulled out with a season-ending knee injury.

The Spaniard was scheduled to return to the court at the season-opening Brisbane International starting on Saturday, but has now had to concede that he’s not yet ready for competitive tennis.

“I am sorry to announce I won’t be coming to Brisbane this year. My intention was to play, but I am still not ready after last year’s long season and the late start of my preparation,” Nadal tweeted on Thursday.

I am sorry to announce I won’t be coming to Brisbane this year. My intention was to play but I am still not ready after last year’s long season and the late start of my preparation.
I had a great time there and it was a great start to the month I spent in Australia

— Rafa Nadal (@RafaelNadal) December 27, 2017

He indicated he now planned to come to Australia early next month before the Australian Open – the year’s opening grand slam event – at Melbourne Park starting on January 15.

Nadal reached the semi-finals in Brisbane early this year before returning to contest his first grand slam final in two-and-a-half years three weeks later at the Australian Open.

But having has also withdrawn from the Fast4 exhibition event in Sydney on January 8 alongside Nick Kyrgios, Alexander Zverev and Grigor Dimitrov, the 16-times major winner is now in a race against the clock to be fit for Melbourne Park.

“I had a great time there [in Brisbane in 2017] and it was a great start to the month I spent in Australia,” Nadal said.

“I will be seeing my Aussie fans when I land on the 4th in Melbourne and start there my preparation for the Australian Open.”

Serious concerns over Nadal’s fitness first surfaced last week when he cancelled a planned training block in Majorca with Portuguese player João Sousa.

And Nadal may not be the only high-profile scratching from the Brisbane tournament.

Five-times Australian Open runner-up Andy Murray has delayed his planned Christmas arrival to Australia because of a chronic hip injury.

The hip problem has prevented Murray from playing for the past six months and seen him slip to number 16 in the world.