Only argument to bench Sagna is because of the French thing as I read on here he has found it tough this week. But even then I don't think its a strong enough argument.
I can't see how a 3-man midfield can work, as it would mean KDB on the right where he has done just about nothing (either that or start him false 9 and no striker - again that didn't work). Navas would also likely make way, and he definitely has to start - I can't see Sterling being benched and if he was it might feel like the first psychological battle won by the scousers.
The only way I ever want to see 3 midfielders is like Sevilla way, with both Fernandinho and Yaya having a license to get forward, Fernandinho in particular would be a major asset nicking the ball in the opposition's final third.
Hart
Sagna
Otamendi
Mangala
Kolarov
Yaya
Fernandinho
Navas
KDB
Sterling
Aguero (it feels good to type those letters again!)
I wonder what he'll do with the bench - I bet he picks both fullbacks, Demichelis, Fernando and Delph, leaving only Iheanacho as an attacking option, and no Roberts.