I think the break gives Djokovic an advantage but at the same time I could see Murray winning the 4th set. I watch enough sports in which crazier things have happened. I still do think Djokovic will win the whole match but I could see this match going in 5 sets.
Like I always said, the thing with Murray other than his forehand and very weak second serve is that he lacks aggressiveness or his mental strength.
When Murray won those last three games in the third set, he took it Djokovic. He was aggressive and didn't allow Djokovic to dictate points. That's the Murray I want to see against the Top 3 players. Yes, he might not be as talented as the top 3 players, but he is good enough player to beat them on any single day. He just need to bring the aggressiveness throughout the match not just when he is down a set or during the start of the match.