We've heard a couple of whisperings to the contrary earlier in the week, but according to Chelsea manager Andre Villas-Boas, injured midfielder Michael Essien will not be included in Chelsea's Premier League roster until January:
I can play a little bit with [the squad]. It depends. We have a couple of under-21 players, and we have Essien's injury. We'll only register him in January, as he knows. We can play a little bit with that.
Keeping Essien off the squad allows for the acquisition of another non-home-grown player (there are a maximum of seventeen such players over the age of 21 allowed on a Premier League squad while the transfer windows are closed, and Chelsea have sixteen on the books*). This is actually very important news in terms of Chelsea's transfer acquisitions - they're giving up on the possibility (however remote) of having Essien return early in order to hold open a slot for a new international purchase.
*As it stands, Chelsea can only register twenty two players over the age of 21, as well as a number of excellent young talents in Josh McEachran, Romelu Lukaku and Oriol Romeu who don't need to worry about anything just yet.
No matter how tiny the likelihood of Essien recovering before the winter transfer window opens may be, the only reason to leave him off the squad is if you're confident that that empty slot will be filled by someone else. Otherwise, leaving it open is pointless - longshot bet on the Bison is far better than no bet at all and a smaller squad. Leaving Essien off is clear, clear evidence that Chelsea are going to make another purchase before the end of the window. Based on Villas-Boas' previous statements, it'll be a midfield player.
Perreira? Modric? Moutinho? Someone else?