He doesn't hold two grandslams.
In fact, at 23 and struggling with injuries, he only needs to win the US Open to match Federer's recent feat of having won every Grand Slam at least once...
Everyone in roughly the past 1 and a half year beats Federer regularly in any tournament aside of Grand Slams. That's when the best show their best tennis. Federer at Grandslams = different federer at small fry tournaments. The same goes for Nadal.
Federer beat Nadal last year on clay in Hamburg and everyone thought he had a chance against nadal at Roland Garros... he was allowed 3 games and got absolutely humiliated by a completely different Nadal.
He's the world no.1 and fecked Federer in their last three meetings in Grand Slam finals. At 23. Yes, I'm clearly wrong...