I would not take the risk of playing a massively weakened team , and I would not go for 4-4-2 as that will invite them to come and attack us and with it being the FA cup , you never know .
I would go for :
-------------------Hart----------------
Richards----Vinnie K---Lescott----Kolarov
------------------Vieira----------------
-----------Barry---------Yaya--------
Silva------------------------------Milner
-----------------Dzeko--------------
Any win will do but I think with three in the middle ,we will be comfortable. 4-0 City . Dzeko x 2 , Silva , Barry