It's a shame he felt he didn't play well today (only he knows if he did or not) - he seemed to start ok. The stats for the first set were close, despite the score. It's hard to guage a level, playing someone for the first time. And Hubi is a very difficult player, and quite underrated, really. Rafa maybe feels there is unfinished business in Rome - but in Madrid he did as much as he could.
I don't think he has anything to prove- he's won in Rome 10 times. No-one can take that away. And he lost to a top 10 player, not an unknown qualifier.
But it's probably a difficult loss- and he's maybe questioning if it is worth going to RG.