Allardyce told BBC Radio Lancashire: "One would like to say that when Paul Robinson gets fit I find it difficult to leave Jason Brown out.
"We hope that Jason will step up to the plate and give us a great performance."
Brown replaces Robinson who is out for a month with a torn calf muscle
Allardyce added: "His record has been very good when he's stepped in.
"We found some first team football for him in the Carling Cup in the earlier rounds and in the FA Cup so he's done well in those.
Brown joined Blackburn from Gillingham summer 2006 but has found first team opportunities limited by the form of Robinson and his predecessor Brad Friedel.
Brown said: "It's a great opportunity and I'm looking forward to it very much. It's sad what's happened to Robbo who's a good friend of mine.
"It's part of life. As one door shuts another one opens."
Source: BBC Sport
Source: BBC Sport