Australia coach Eddie Jones was scheduled to name his starting team tomorrow but said today he would wait until Thursday before making a final decision on Andrew Walker.
The Australian winger told Jones he woke this morning with a sore right knee. X-rays cleared him of any serious damage, but medical staff told him he had tendinitis.
Walker missed Australia's 14-14 draw with South Africa a fortnight ago after failing to board the team's flight to Perth.
He later told the management he had left the team to visit his pregnant wife and was recalled after he apologised and promised not to do it again.
There was some good news for the Wallabies today, however, when fullback Matt Burke returned to training after missing yesterday's practice session because of an ankle problem.