Rafael Nadal has withdrawn from the Brisbane International with an ongoing knee injury but says he still intends to play at the Australian Open.
The world number one had already pulled out of the Mubadala World Tennis Championship in Abu Dhabi this weekend.
"I am still not ready after last year's long season and the late start of my preparation," said Spaniard Nadal, 31.
Meanwhile, Roger Federer does not "think it's normal and realistic" to match his 2017 exploits next year.
The 36-year-old Swiss, who has arrived in Australia to play in the Hopman Cup in Perth, won the Australian Open and Wimbledon in 2017.