The World Cup winner and two times Lions tourist , is suffering from a strained right calf muscle.
There is no clear indication at this stage about its severity but the injury is yet another concern for England head coach Andy Robinson.
Robinson is understood to have settled on his starting XV for the Millennium Stadium clash, which is set to include Dawson for a first Test appearance of the season.
If though, he is ruled out, then Robinson must decide whether to retain Gloucester's Andy Gomarsall or promote exciting Leicester prospect Harry Ellis.
Robinson is already without the likes of Jonny Wilkinson, Mike Tindall, Will Greenwood, Richard Hill and Martin Corry through injury, and he could now also lose Newcastle centre Jamie Noon.