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.
The first time (out of two total) I bet on a sports result was Nadal versus Soderling French Open 2009 (Nadal -x.5 games).