Modric and Palacios are transfer window injuries. There are potential negotiations left unresolved and we can't risk the players becoming cup-tied. That's why I would also be surprised to see Crouch tonight.
Personally, I don't see the point of starting Rafa if he's just coming back from injury. Let him play 30 minutes if needed but save him for United. We don't need a player of that caliber to beat Hearts anyway. I'm probably wrong b/c Harry never seems to do what seems obvious but I would use:
Gomes
Walker Kaboul Dawson BAE
Lennon Livermore Kranjcar Bale
Defoe Pav
Subs: Rafa, Rose, Townsend