It's notable that Murray's the one hampered by a day less recovery - a reversal of the US Open. I suspect that this will be one of the deciding factors tomorrow, with Djokovic emerging victorious after Murray runs out of steam.
I'm not worried about the physicality of the match. Andy's fitness is ridiculous.
The only concern I have is how he will be emotionally. That was one hell of a match yesterday and a significant Slam notch on his belt which I'm sure was another great relief for him.