In fact you could argue that Federer chokes against Nadal, Djokovic chokes against Federer, and Nadal chokes against Djokovic. Watching tennis nowadays you don't see ANYONE step up their game on a big occasion. And, if, in a slam, a lower ranked player gets a lead they always blow it and lose without exception. If tennis players in general just had a MODICUM of mental strength the game would be more interesting. Schiavone and Nadal are my models for mental strength even though I hate both of their games.