Bantams boss Phil Parkinson has revealed that City defender Andrew Davies was forced off during Tuesday's draw at Bristol City because of a calf problem.
It seems the calf injury is a similar issue to one that has troubled the popular centre half in the past.
Parkinson admitted that Davies had been dealing with the problem since the Barnsley game over a week ago and it is something City will need to check over again ahead of future games.
Parkinson said: "He (Andrew Davies) has had it since the Barnsley game.
"It is frustrating for me, the rest of the staff and obviously himself because we don't really want a scenario where we are worried he is going to come off during a game.
"Coming to the league leaders, losing him clearly wasn't ideal and it meant having to scuffle our defence around again.
"That is why tonight's (Tuesday) result is such a good one. We've had no Darbs (Stephen Darby) and then we've lost Dava (Andrew Davies) during the game.
"I have to say, however, that Alan Sheehan came on in his place and helped the marshal the defence really well.
"He was obviously unhappy to be left out of the team originally but we have to make tough decisions for certain games.
"He showed a great attitude when he came on. It was the sort of performance that will get him a lot of creditability among the other players."