A win is a must for Juventus. They can easily climb up as long as they take three points from Milan soon. They shall focus on how to beat their next opponent, and may be struggle to do that.
Juventus's gap to the Napoli is very thin. They can climb to the first position when their opponents will miss three points soon.
I haven't seen a rumor about Juventus's January transfer to buy a new player, but they will sell Fagioli for 25m.
I thought Milan had turned things around with their victory over Real Madrid, but I was wrong. They lowered my expectations against Cagliari. Milan lost points away to Cagliari despite leading twice. The points difference in Serie A is starting to build and every week is becoming more and more important. With the points so close and so many teams in the race, Milan should not lose to Juventus in this match and should even win in order not to widen the points gap. However, in my opinion this is not realistic. Juventus have been playing much more consistent football than Milan throughout the season. While Milan have problems with Fonseca, Juventus seem to be in harmony with Motta. Having won their last two games in Serie A, I think Juventus will not lose in this match.