The England under-21 man has yet to begin heading the ball again following the fractured sinus cavity he sustained in the home defeat to Reading, and which later forced him off at half time in the victory over Hull City.
It was expected that the international break would allow some of the Canaries' walking wounded to regain fitness, but with boss Nigel Worthington prepared to wait until the latest possible moment for news on Ashton, he may actually end up worse off than before.
Youssef Safri incurred a groin injury playing for Morocco, while Leon McKenzie, Peter Thorne and Jason Shackell all remain sidelined. After admitting he made a mistake playing against hull, Ashton himself said he would not be prepared to play unless he felt 100 percent ready.
The crisis comes as City bid to extend an improved sequence of results that has pushed them into the top half of the table and onto the fringes of the play off race. The Millwall match will give the chance to some fringe players to stake a claim to a regular spot in the way that Paul McVeigh has since an excellent performance against Plymouth.