There is increasing doubt over the fitness of tournament favourite Serena Williams after she cancelled a scheduled training session today.
Williams, the third seed, rolled her ankle during her first round win over Romanian Edina Gallovits-Hall.
She was forced to take an injury time-out and had the right ankle heavily taped but went on to complete a 6-0 6-0 win.
Williams was upbeat about the issue afterwards but said she would know whether it was a serious problem within 24 hours.
The American's second round appearance is now under a cloud after she told tournament officials late on Wednesday that she would not be practising in the afternoon.
She said she may have scans depending on how the injury develops.
"That's definitely optional. I'm going to play it by ear," Williams said after her match.
"I would love to see the next few hours how I go, and then I'm going to decide what to do next at that stage."
"Obviously there's pain, obviously there's swelling. So it's going to be really important to see how the next few hours unfold."
Williams is the reigning Wimbledon and US Open champion and has won the Australian title five times.