Spot on Sir Swish. The key to Juan Martin's victory was his variety and mixing pace. This is how Djokovic can get beaten. Not that it always works, but I believe it is the best chance one has. Djokovic usually eats up consistent pace, even if it is very fast. But mix in some slow stuff and then pound it, and it discombobulates Nole. And you have to hit to the right spots on the court. You can't go too wide on the forehand, Nole loves hooking, slapping from outside the court. No, when he is on the run to his forehand side, better to go about 2 meters inside the line, but deep, and many times Novak will put it in the net. Now on Nole's backhand side, better in general to hit with more angle and good pace so he can't use his up the line shot. Then there is a good chance that Nole will hit it out. But those winning shots have to be set up with off pace stuff, the lower the better. Then occasionally, Del Potro mixed it up by going toe to toe with Nole and just pounding forehands with him, and Del Potro got the better of him more than not.
Federer used to have this strategy all the time, but lately he seems to be fixated on trying to outhit Nole from the baseline too much, without giving enough off pace lower bouncing shots, and varying the depth of the slices.