First possibility and the most likely one:
Murray is winning this. He hasn't lost a set, has clocked the least 'Time on court' stat, the other two are coming off five setters, with Djokovic possibly facing another tough battle to add to his TOC.
Djokovic is winning it IF Federer beats Murray. Why? Because that will exact even more juice to bring No. 31 and five set format into play to the detriment of Federer.
Nadal could win it. Weirder things have happened.