Fed is clearly practicing his drop shot for trickier matches to come. His disguise when playing the shot is simply class. It could be a shot he plays a lot against Nadal if he they make the final. I like the 'play' as Nadal is very deep and yes he's fast but a quality drop doesn't leave much room for error if you do get to the ball in time (your always hitting up). Generally, if Fed comes to net he can cut off most responses. But, I said it has to be quality. From what i've seen with the amount disguise and cut (spin) it's could be a smart play. Very few players are attempting the shot at the moment.