Australia look set to lose Berrick Barnes and Timana Tahu for the remainder of their European tour.
Barnes, 22, suffered suspected posterior cruciate ligament damage early in the Wallabies' 30-20 victory over Italy in Padova on Saturday.
The Queensland Reds fly-half will undergo scans in London but is expected to be ruled out of Saturday's Cook Cup clash against England at Twickenham plus Australia's appointments against France, Wales and the Barbarians.
Tahu, Australia's latest dual-code international, damaged hamstrings in the same game and is also likely to miss the rest of the trip.
Australia travelled with a squad of 34 and coach Robbie Deans is not considering calling for replacements.