When Nadal is healthy nobody can take him down at RG besides Nole, but Delpo or Soderling at good day can beat average Nadal there for sure
This. And even then it has to be said that this is based on 2 clay tournaments last year, one of which (Madrid) has very bad conditions for Nadal anyway. So far even Novak has not managed to take more than one set off Nadal at RG. Only Soderling and Isner have taken 2 or more in a match.
Novak has the best shot by far but if it's Nadal at his best then no one has a chance at RG. There are Novak fans who seem to think Nole 2.0 could have beaten Nadal in 2008 at RG - no chance - that was the best player on clay ever playing at his very best - no one was getting 3 sets.
Outside the top 4 you have to think it's Del Po and no one else really. Ferrer is not as effective vs Nadal on clay - he could get a set but not 3. Isner potentially but think Nadal would have learnt from last year... Nadal needs to just make sure he stays in the top 2 till RG so he can't meet Novak before the final.