Djokovic is a bit overrated here. He's very good when he has nothing to lose (match point down) but i saw him fading badly in a lot of big matchs in his career except 2011.
This year, he should have won against Murray in the USO, he missed many chances against Federer at Wimbledon, and he almost chocked badly against Nadal in the AO. Luckily for him, Nadal couldn't take his chance.
In his prime, Federer was clutchier, but these days he's weaker, so i put him behind the serb.
Nadal is on another planet, he's just a mental freak, almost inhuman.
The guy couldn't lose a big match where he has a shot at winning. In his entire career, well, he failed only two times, Wimbledon 2007 and AO 2012. But how many of these matches he managed to win? A billion.
Good post, still think Nole is very clutch though. Definitely top 2