As McEnroe said, Justine's greatest asset is her strength of will. If I hadn't seen her fight back from the brink of elimination so many times, I'd say she's lucky. But luck has little to do with it. She wills herself to victory.
It would be interesting to compile a list of the number of times Justine has fought back
to take the third set of a match. Some of the more memorable I can recall:
Australian Open 2003 against Davenport
Dubai 2003 final against Seles (saved a match point in the 3rd)
U.S Open 2003 against Capriati
2004 Olympics against Myskina
2005 French Open against Kuznetsova
I'm sure there are at least a dozen others.