Jason De Vos has a three inch blood clot in his thigh and Joe Royle admits that he will be surprised if the defender is fit for Saturday.
The Canadian international sustained the injury in the first five minutes of the 5-1 win over Sheffield United, limping away from a corner.
Despite efforts to 'run it off', Jason was replaced by Matt Richards midway through the first-half and Joe told the Club website: "I will be surprised if he's out there at Burnley on Saturday.
"He has a three inch blood clot in his thigh but the physio team are working hard to disperse it and we will see how it goes.
"At best I'm hopeful but no more than that.
Jason - blood clot
"Tommy Miller and Fabian Wilnis are fine though. Tommy has taken a knock, as he often does given the way he plays but he'll be fine and there has been no reaction to the injuries they picked up against Preston on Saturday."
Both players were substituted in that match, with Fabian suffering cramp in a hamstring and Tom a bruised calf.
