CAMELOT FANTASIES

I can't agree more, general and Lady TT. 

If Rafa stands more than 1-2 meters behind the baseline, he is doomed.   Gone are the days when he go back to the fence and return.  These balls are too light and quick for him to defend angles from downtown Melbourne.

Unfortunately for him, if he stands too near the baseline, he has to hit the quick ball on the rise and he doesn't have time for his massive topspin swing.  His timing and positioning have to be very precise.

So he's sort of damned if he does, damned if he doesn't.

In these conditions, he'll have to take care of his serve first, get about 80% of first serves in, and win at least 70% of them.
Second, he'll have to get the ball back deep and quickly with or without extreme topspin.  Short-mid court balls will be a disaster against this Federer. 
Third, his forehand down the line and cross court backhand have to be impeccable.  He can't spray them like he did against Dimitrov.
Fourth, he'll have to be ready to pass and lob with accuracy and impunity as the Swiss Assassin will be looking to come in and end the point at every good opportunity.
Fifth, he needs to keep his unforced error count down to around 5-10/set and get as many balls back as he can to force Federer to make the errors.

He can do it, but it will be a tall order considering he hasn't played anyone ranked higher than #16 so far.  He's not as hardened as Federer and he hasn't played as well.  To expect him to play well suddenly, just because it is Federer on the other side of the net might be a lot to ask.

Still, he has a tremendous amount of motivation and as we know, tenacity.  So Federer also has to serve very well and can't afford one of his games with a high number of errors or he'll just give the match away.  If they both play well at the same time, it should be an interesting match for sure.  It hasn't happened lately, but one can always hope.

Respectfully,
masterclass