What's to defend at the WTF? Not much.
Yeah, I'm really hoping he gains there. Djokovic doesn't have much to defend either though, Fed won so he's obviously most likely to get hit. Djokovic will probably be favourite to go world no1 after the WTF, Fed has also got Paris and Basel wins to get hit by as well. Unfortunately Murray's got the Shanghai win to get hit by before the WTF as well, Djokovic didn't do anything there either.
Basically Djokovic is most likely to be the world no.1 at the end of this year.