Nadal has said after his first round win that he felt pressure going onto that match. I believe he will feel throughout the tournament, but as he advances it's probably gonna disappear if he's really focused. If not, then it might be too much for him, even though his play is excellent on the surface.
There's also the matter of courts. Clay and conditions are different in every court, and this was his first time in Philipe Chatrier. I guess he had some nerves in this match too, it's the stadium that he could see his glory one week and a half from now, but on Friday is bound to be different, though he's gonna taste the flavor of the French crowd