Twice Wimbledon champion Petra Kvitova withdrew from the Brisbane International with a viral illness on Monday.
The 27-year-old Czech was unable to take the court in her first round match against Estonian Anett Kontaveit and was replaced in the draw by lucky loser Heather Watson.
"I'm really disappointed to withdraw from the Brisbane International," Kvitova was quoted as saying on the WTA website.
"Unfortunately I picked up a virus on the flight to Australia and I haven't been able to get healthy in time to play here.
"It's always a fantastic and competitive place to start the year so I'm sorry not to be in the draw."
The former world number two required four hours of surgery on her left hand in December 2016 after being attacked by a man wielding a knife who had gained access to her apartment by posing as a utility worker.
Kvitova returned to action, after months of rehabilitation, during the French Open in May and went on to win the Aegon Classic in June.
She last played at the Tianjin Open in October and was preparing to open her 2018 season in Brisbane.