Utility back Staniforth was likely to start on the bench against England
England v Australia
Stade Velodrome, Marseille
Saturday, 6 October
Kick-off: 1400 BST
Live on BBC Radio 5live and the BBC Sport website
Australia utility back Scott Staniforth is the latest player to be ruled out of his side's squad for Saturday's game against England because of injury.
Staniforth has an on-going shoulder injury which has ruled him out of the Rugby World Cup quarter-final.
He was expected to be on the Australian reserves bench because of his ability to cover wing and inside centre.
Staniforth has not played since the pool game against Fiji and may be sent home is he fails to improve quickly.
"We'll make a decision after Saturday," said Australia coach John Connolly.
"But Scott's important to us because of his flexibility...he helps our bench a great deal so he is a big loss."
Australia have already lost wing Mark Gerrard and backrower David Lyons for the tournament and fly-half Stephen Larkham is a doubt.
Larkham has already been ruled out of the quarter-finals after undergoing two knee operations and would be uncertain to play in the semi-finals if Australia beat England.
But Connolly added: "We are in a reasonable place.
"The goal was to get to the quarter-finals with some petrol in the tank.
"Confidence, belief, composure, patience come into play when you get to this stage of a tournament and belief is massive, confidence is how you play the game that's going to get you through to the end is also a big factor."