Alex Ferguson is well noted as the best in the business when it comes to playing mind games with his fellow managers. He's great at talking to the media and getting them to spin stories to his liking, as well as tricking his opponents into thinking a certain way. While there is often a direct intent and some serious skill involved in Ferguson's games, he really has become a cult of personality at this point. Even when he's not trying he's playing mind games, and sometimes silence is his best weapon.
Right now, it's unlikely that Carlo Ancelotti knows how Ferguson is going to set up his team. He's an intelligent man and a good manager, so I'm sure he can come up with a very good guess, but the Manchester United squad, along with Ferguson's willingness to change his team on a regular basis always keeps people thinking. I've gone through Ferguson's team selection over and over in my head and I can't settle on anything. It's possible (read: very likely) that Ancelotti has a better idea than I do, but it's also possible that he's clueless.
The implication there is not that Ancelotti is a clueless manager, but that it's not easy to get a grasp of what Ferguson is going to do from game to game. There are any number of approaches he could take and any number of players he could pick. On multiple occasions, he's gone with a 4-4-2 setup when we were fairly certain he would go with one central striker, and on just as many occasions, he's gone to a 4-5-1 with Park Ji-Sung on the wing when we were sure he would attack.
I think that Ferguson is going to play for a draw with Park and Antonio Valencia on either side of Wayne Rooney, leaving Dimitar Berbatov, Javier Hernandez, Nani, and one of either Paul Scholes or Ryan Giggs on the bench. I wouldn't be surprised to see him do something entirely different. How about starting Berbatov up front and Rooney on the left? What about moving Nani over to the left and going for the jugular? Maybe Park should play on the right because Rafael needs more support in defense than Patrice Evra. And he wouldn't play 4-4-2, would he?
This is what Ferguson does to people. Hopefully for Chelsea fans, Carlo Ancelotti is a hell of a lot smarter than I am.