Czech star and former champion Petra Kvitova withdrew from the Brisbane International due to a virus.
Kvitova, 27, was set to face Anett Kontaveit in the first round of the WTA Premier event before announcing her withdrawal on Monday.
The 2011 champion and two-time Wimbledon winner revealed she was battling a virus.
"I'm really disappointed," Kvitova said, via the Brisbane International.
"Unfortunately I picked up a virus on the flight to Australia and I haven't been able to get healthy in time.
"It's always a fantastic and competitive place to start the year so I'm sorry not to be in the draw."
Heather Watson took Kvitova's place in the draw.