Re: Your expectations for Djokovic in 2013
Expect AO win and to end the year number 1.
Picking Nadal to win FO and expect Djokovic to lose in semi-final or final to Nadal.
Federer or Murray should beat Djokovic in semi-final or final at Wimbledon.
USO will be won by either Murray or Djokovic.
Overall, expecting 1/2 GS and end year number 1.
The current greatness league of active players in order of achievements to date (a factual comparison rather than fan biased assessment):
Federer 17 GS, 6 Year End Masters, 23 Master Series.
Nadal 14 GS, 27 Master Series, 1 Olympic Gold.
Djokovic 7 GS, 4 Year End Masters, 20 Master Series.