Here's my bold prediction:
At least one of the Big Four won't get to R4.
Nadal losing to Söderling was very much the only big upset loss in years for the Big Four in slams before last year. Otherwise they had always escaped from upset losses. If they couldn't raise up their game, then the opponents became too afraid to win a big name.
But during the last year, Rosol, Darcis, and Stakhovsky have showed the big names can't afford playing badly, even guys ranked lower than #100 can beat them when playing badly. And now the lower-ranked guys have the faith not to choke when they are winning a big name. Roger and Rafa have had upset losses recently and Murray was in trouble against Cilic and Verdasco on his way to USO and Wimby titles. Djokovic has been the most impressive in early rounds but he had the tough matches against Wawrinka at AO this year and against Seppi at RG last year. One of those guys won't make the R4 at USO, mark my words.