No one ever has a good chance to win the CYGS.
However Djoker in 2013 has a better chance than most, I'd say around 20%.
I don't see him winning Wimbledon though, I think his victory in 2011 was something of, if not a fluke, than an unrepeatable victory. I think Murray will triumph on home soil in 2013.
Sloane Stephens and Laura Robson: future WTA world No 1 and 2.