World number 11 Petra Kvitova is set for a delayed start to the new season after pulling out of the Hopman Cup due to her foot injury.
The Czech suffered a stress fracture in her right foot, but was still hopeful of featuring at the team event starting January 1.
But the two-time Wimbledon champion said her recovery had been slower than expected, leading to her withdrawal on Tuesday.
"I am so disappointed that I cannot play at the @hopmancup," Kvitova wrote on Twitter.
"The results of an MRI have confirmed that my foot is healing, but not as quickly we would have liked.
"The Hopman Cup is a fantastic event and I'm sorry I won't be able to represent my country there."
Lucie Hradecka replaces Kvitova for the event in Perth, teaming up with Adam Pavlasek.
The setback is a blow to Kvitova's Australian Open preparations, with the left-hander having failed to go beyond the third round at the year's first grand slam since reaching the semi-finals in 2012.