Azarenka announced half an hour before the scheduled start of the match that she had to withdraw after having treatment for an infected big toe on her right foot, saying she couldn't risk aggravating the problem ahead of the Open, which starts on Monday week. The 23-year-old Belarusian said she had had the problem for 10 days, but the infection had got so bad that she had to visit a doctor and have part of the toenail removed.
"It just got infected from a bad pedicure experience. I had somebody who gave me an infection," she said.
"The doctor said it happens a lot."
In the Brisbane final Williams will meet Russia's Anastasia Pavlyuchenkova, who came back for a 4-6, 6-1, 6-2 semi-final win over Lesia Tsurenko of Ukraine.