Vidal is great to watch. But to have him and both Pirlo and Marchisio as starters would mean than Marchisio will be placed as LM.
As it was obvious again today, we are playing with 2 CMs (one deep playmaker, linking defence with the rest of the team, aka Pirlo and one a bit forward to link the midfield with the attack, an ideal place for Vidal to be) and 2 offensive wingers (able to drive in, create havoc, wide our offensive front and help to carve open tight defenses, not exactly the ultraversatile's Marchisio strongthest point)
So we might have to compromise smth, somewhere.
Against the smaller teams, we can savor all tha spectacle and field the magnific 4 (Pepe, Pirlo, Vidal, Marchisio)
But against the strongest team, it is mandatory to use them, instead of an inferior winger (Elia, Krasic, Giacche, EstiG) as Marchisio adds up to our overall quality and can defend better than any of them. An imporant thing in the important matches.
Vs the smaller teams, we can try a more offensive scheme and lesser quality overall.
So Conte opt to rest Vidal a bit and risk Giacche to see if he really is as good, as some thought.
It was a wise opportunity and Vidal will have much more stamina to offer for the great match ahead, we will need the 101% of his stamina for this one.