Ah So.
Djokovic will drop to12,900 ranking points.
If Murray wins the tournament he'll be on 10,485.
If Murray reaches the final he'll be on 10,085.
If Murray loses the Semi Final he'll remain on 9,845.
Basically if Murray wins it he's went from being 4,700 behind to 2,500 in the space of 2 weeks. Almost halfed the points difference, he's closing in.