And McLeish admits it will be difficult not to put James McFadden back in the squad following his recovery from a knee injury, despite the star striker not being back to full fitness.
He told the club's official website: "We have food for thought with McFadden, [Marcus] Bent, [Stuart] Parnaby, [Kemy] Agustien, Djimi Traore, all these guys are available again and it could be a case of how they look in training over the next few days.
"They've looked ok so far but where do I fit them in given the decent performances of the players in recent games?
"McFadden is bursting to get back in. Of course with a player of his ability I can't ignore that if I think he is at a good level. It's doubtful any of the others will start unless we have massive problems.
"I think we have to certainly treat this one as a cup final from the point of view we are at home. I don't like using that word must win because it looks desperate but we certainly have to play to our top form and back to the Bristol type performance and Southampton type performance which is what I am looking for."