I assume this will be the line up:
Buffon
Lichtsteiner-Bonucci-Chiellini-Evra
Marchisio-Pirlo-Pogba
Vidal
Tevez-Morata
--------------------------------
Buffon
Lichtsteiner-Bonucci-Chiellini-Evra
Marchisio-Vidal-Pirlo-Pogba
Tevez-Morata
Like the games against Real Madrid, when Juve are being aggressive they will go with the 4-3-1-2 and when they drop off it'll be 4-4-2.
The question will be just how bold Juve are prepared to be.
With the 4-3-1-2, you can put huge pressure on Barca's midfield and make it extremely difficult for Barca to work the ball forward. The danger with that is that you will leave at least one of Alves and Alba quite free and you will need the defence to push quite high up to maintain the proper shape of the team. Barca showed against Bayern that they are far more prepared to play the ball long than they used to be, but Juve have to back their defence to deal with those long balls better than Bayern did. Bayern dealt with them horrendously.
With the 4-4-2, you are letting Barca have more comfortable possession in deep areas and focusing more on denying them space in key areas.
The danger is likely to come in the transitional moments between the shapes. If Juve press up in 4-3-1-2 and get it wrong, there will be huge danger if Barca go quickly and attack before Juve can get the men back behind the ball and into the 4-4-2.
Pressing with the 4-3-1-2 would feel an awful lot more secure if you had Marchisio as the spare man behind the midfield rather than Pirlo, but I can't imagine Allegri dropping Pirlo for such a big game. Similarly, one could argue that Barzagli would be much more comfortable playing against Barca's type of forward than either Bonucci or Chiellini, but I can't see a change being made there either.
One change I might make to the posted team, would be to swap Pogba and Marchisio. I back Marchisio to contain either Iniesta or Rakitic, but I'd fancy Pogba's chances of dominating Iniesta in the way that he probably couldn't do to Rakitic due to Rakitic not being a weakling. Shifting Pogba to the right may also open up the chance of getting crosses from the left to him coming in at the back post against Mascherano and Alba and those guys wouldn't have a hope of stopping Pogba in the air. On the other side, Pique is obviously a big guy and Alves is better than Alba at putting in a challnge to put an opponent off, even if he isn't going to win a header.
This Barca is harder to stop than any Barca we've seen since Eto'o left them because they've finally got a centre-forward who runs in behind and opens up space for others. When Allegri's Milan were doing well against Barca, the centre-halves never had to worry about anyone running beyond them, so it was much easier for them to control the space between the defence and the midfield.
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