Wallabies inside centre Pat McCabe will be sidelined for at least three months after scans revealed he has a fractured neck.
According to AAP, McCabe's place in the squad will be taken by Melbourne Rebels centre Mitch Inman, who is on his way to join the Wallabies for the remaining two games of the European tour, against Italy and Wales.
Inman's Rebels team-mate Cadeyrn Neville is also joining the squad as cover for injured lock Kane Douglas, who is expected to be ruled out of the tour with knee ligament damage.
McCabe suffered the injury in Australia's tour-opening 33-6 loss to France and was withdrawn from the Saturday's Test against England.
Ben Tapuai, who played at ouside centre against les Bleus, will now be the starting number 12 at Twickenham.