Grella is still recovering from a hamstring injury, Dunn has a thigh problem. The injuries have kept both players out of pre season warm up games.
"They have missed most of the pre-season games and are out of the running," Allardyce told the Lancashire Telegraph.
"Dunny and Grella definitely won't play a part - unless we pick up loads more injuries - because they have only had 45 minutes between them."