Imo a 4-2-3-1 is the way to go. If we play Gio then the need for a more defensive left back would make sense, with some decent attacking capability.
on the other hand you want to balance it out by having your other fullback be a good wide threat. that is the ideal situation imo, but it doesn't always have to be that way for s team to be successful.
Caceras-Kjaer-Chiellini-Criscito
------Melo--injuredsoko----
Silva------Diego----midget
-----------Trezeguet--------