Evans was forced off early in the win at his old club Bradford City after a heavy challenge from Bantams captain Michael Flynn.
The wide man will have a scan to find out the extent of the damage after watching the rest of the game with the aid of crutches.
Boss Andy Scott said afterwards; "He's not looking good. He has got a swollen ankle which will need to be looked at which is a massive blow, not just for him coming back to his old club, but for us because he is a major part of what we do."We have got to make sure that we look after all the lads now as we've alot of games going into December, we have a reserve game on Monday and we'll have to review who we play."