no_instance

I think we are going to be having a combination of Azpilicueta - Rudiger - Luiz at the centre back positions. 
Rudiger is pretty solid, with some good sense of positional play, and he is going to be better than just a mere back up option. 
I will like to see Zouma go on loan, he needs a club where the expectations will not be as high as Chelsea's, getting games week in week out. He will soon be back to his top form and Chelsea will know what to make of that by next summer. 
That leaves Cahill and Christensen on the bench. I believe they will get a decent amount of games too, I will give priority to Christensen however. 
That by any stretch of imagination means Chelsea have the best centre back combination in the premier league. (I know we fans always want more though)