Number eight Wycliff Palu has been ruled out of the tournament with a serious left hamstring strain.
He's returned to Australia with a replacement to be named at a later date.
But midfield backs Pat McCabe and Rob Horne will both stay in New Zealand, with their shoulder and cheekbone injuries respectively better than first feared.
McCabe will be available for the quarters while Horne will be back for the semifinals should Australia qualify.
Wing Digby Ioane is continuing to improve from his dislocated finger and is expected to make a return in the quarterfinals.
