It's definitely a hard team to predict, with virtually everyone fit.
I think we'll line up as follows:
Hart
Zabaleta
Kompany
Demichelis
Clichy
Fernando
Fernandinho
Milner
Navas
Silva
Aguero
Having said that, there's an argument for one of Lampard/Jovetic/Dzeko starting to give us more attacking threat and physical presence, which could be important given Chelsea's power and strength (especially on set pieces). They're a big, imposing side with Ivanovic, Terry, Cahill, Matic and Drogba.