Boss Kevin Blackwell said: "He (Gary Speed) is improving and we will give him as long as possible to prove his fitness. He suffered a bit of a spasm in his back early on against Wolves which made playing uncomfortable, but he was sensible enough to come off and not to make it worse.
"He has a chance but if he doesn't we have a very good squad with strength in depth in every area and whoever comes in will do a good job.
"Matthew Spring replaced Gary on Tuesday night and he is a good player who has been promoted from the Championship before with Watford. He can score goals and I am surprised that it took him until Tuesday for him to get off the mark for us."