Carlisle has a slight strain and Kevin Blackwell will take no risks with the newcomer.
The boss said: " Aaron definitely won'y play tomorrow. Clarke could play if we need him, but we have plenty of other games when we get back and I'd rather give him a bit more time and look at him at home if possible.
" Aaron will have an X-ray when we get home. The injury happened when no-one was near him so we need to look at that and see what the problem is."