Nalbandian didnt really choke against Nadal, Nadal played perfect to save all those MPs, take a look:
http://www.youtube.com/watch?v=qW858OWOoNc
Fed didnt choke against Tsonga because Tsonga was fired up and was blasting winners.
But Roddick/Almagro did choke big time..
Roddick was playing perfect through out whole match but that one volley of his in tie break was massive choke really, I was stunned when I saw it.
Almagro was even worse then Roddick, he blew 5MPs and all on his serves and later on blew his lead when he was serving for match and Nadal wasnt playing anything special so I vote for him.