Djokovic has no threat, maybe Karlovic if he gets to qf.
Stepanek could also be a threat against Nadal.
Stepanek is not 100% but even if he was, he doesnt have the goods to deal with the Clay Monster.
Clay Monster has a slightly tricky encounter with Gulbis who has a big time serve but i dont see him taking down the 4 time French Open champion in a best of 5 sets match. give Gulbis a set at least before the Clay Monster settles down and destroys him.
Fed has a free ride to the semis. i dont see him losing a single set until the semis.