I couldn't see anything specifically (physically) wrong with Novak today but I can honestly say that the surface played its part.
Novak is a slider, he is Mr Elastic with his defensive skills. If he does not have confidence with the court beneath his feet then he is not going to play his normal game. Why risk an injury in the run-up to Roland Garros?
I am sure Rafa & Novak are both glad this tournament is over for them, Rafa is already back home in Mallorca and catching fish :-)
To Rome we go.