This really is a tough one. Roger played pretty well against Kiefer, but I wonder if he might be, like his deputies in world domination, just a bit tired after a heavy schedule. OTH, we all saw what he did to poor Canas, and while he might have beaten Nalby the last time they played, he knows they almost always have tight battles, so he could come out with his sword drawn. Moreover, he has worked hard to turn the head-to-head is in his favor.
As for Nalby: at this point, he has a better chance than anybody not ranked in the top three to pull off the upset. He has started playing great, and has the scalps of top players to prove it. Moreover, when others come in to a match against Fed playing just as well or even better than Nalby is currently, they falter before the first ball is struck because they realize the mountain they have to climb. For David, not only has beaten Federer multiple times, he has done so on a similar surface.
Think Fed might pull it off in two if he comes out firing, but if he gives Nably a chance by letting it go to a third, Nalby takes it. But my predictions have been pretty bad this week. Anyway, to top it off, I hope both play well tomorrow, because I can't wait.