Re: Why does Djokovic need to be on the verge of losing to play his best ?
Hewitt has the same problem.
It is a lot to do with adrenaline. It can be easy to become complacent and, unless you're Nadal, it is virtually impossible to concentrate very hard on every point.
It's not a rule, but please include tiebreaker scores in result threads - A 6-3 7-6(1) score is very different from a 6-3 7-6(9) score.