Personaly I don't see anyones aside from Cilic and Del Potro who can pass him in rankings. I just think that he's going thru a little crisis but he's in great health and can beat anyone on a given day. Nadal is injured and Federer is slower than he was a year ago. And yes, lets not forget that he's only 22 years old. I think his problem is in his head, once he gets everything together he'll be a major threat. With a good draw it can happen in US open
Roddick, Tsonga, Simon and Verdasco if they can play to their potential EASILY. Frankly seeing how Haas did here he could and I think it will be Nole getting upset and slipping more so than people passing him. I'm not saying he'll fall out of the top 100 but he'll be a sort of hoverer between ten and twenty.