He's got serious points to defend in the clay swing. SF at MC, F at Madrid, W at Rome, F at RG for a total of 3,160 between those four tournaments.
Djokovic is still defending more (3,610) through there, but what I think that means is a chance for resurgent Rafa (defending only 1,630 at those four tournaments, 2,130 including W at Barcelona last year) and fearless Fed (defending 270) to catch up in the rankings and make the race for YE#1 interesting.