Nathan Sharpe and Berrick Barnes have been ruled out of Australia's team to play South Africa in the Tri-Nations on Saturday.

The pair joined a mounting casualty list that forced the Wallabies to delay the naming of their team by 48 hours.

The selectors were due to name their side on Tuesday but had to postpone the announcement until Thursday because of the heavy injury toll from last weekend's 19-18 loss to New Zealand in Sydney.

Four players, Sharpe, Barnes, teenage fullback James O'Connor and flanker Rocky Elsom, missed Monday's training session in Perth to seek medical treatment.

Sharpe was then ruled out of the match because of a shoulder problem while Barnes was overlooked after suffering concussion and injuring his neck against the All Blacks last weekend.

Elsom is nursing an ankle injury while O'Connor limped off the field after hurting his leg, although x-rays later cleared him of any fractures.

The Australian selectors are also expected to consider making changes after losing all three of their Tri-Nations matches this season, with prop Al Baxter and scrumhalf Luke Burgess both in danger after being replaced against the All Blacks.