Fate/Zero will be split-2-cour series, like Arakawa Under the Bridge and Kami Nomi zo Shiru Sekai did. 1st cour will be air till December, 2-cour will be airing on Spring season. BD/DVD release will also be separated as 2 different season.
It is actually sort of understandable, knowing that movie quality 1st episode of Fate/Zero had. Thankfully, Nisemonogatari will top the Winter season instead of Fate/Zero. Subarashi-desuyo, Aniplex-san.