Dunn just recently returned from a hamstring injury.
“David unfortunately pulled his hamstring and he looks set to miss three or four weeks which is very disappointing,” Sam Allardyce told Sky Sports News.
“He has just got back from an Achilles problem and I think fatigue may have been a problem and we are all very disappointed for him.”
Big Sam also commented on defender Ryan Nelsen.
“Ryan Nelsen has a very bad eye injury and it is shut at the minute,” added Allardyce.
“We will give it time to get the swelling down and we will wait and see what it is like tomorrow.”