Who's the scariest opponent for Roger Federer here after Nadal?

[The General]

Who has the best chance of beating Federer other than Nadal in this Austrailian Open? I assume Murray since he and Nadal are even odds against each other today, but what about the qtrs and semi's? Davydenko, Djokovic, Tsonga (I doubt Tsonga myself). What are your thoughts? Cilic or Roddick maybe?

Thanks