lleyton is a good choice... he both gives everything and tries to change of strategy, not all the fighters do that... some players fight hard but stick to a losing strategy. similar to chang in that respect ?
federer was (maybe underestimated because he used to hide his emotions).
how would he have made all these amazing winning streaks day-in day-out without severe losses without some constant fight abilities to save him when he had some (relative) bad days ?...
but (unfortunately) recently i saw less fight in him on several occasion (still can't believe how he made this very ugly volley on the match point against murray at doha... usually, when he misses a shot, at least he does it elegantly !
)
well, not easy to remain motivated everyday year after year, i guess...
i'm surprised nobody mentionned baghdatis yet... it's true he's very inconsistent (he has bad days) but he already put some memorable fights, even if he didn't always get the win at the end.
unfortunate examples against agassi and hewitt (who aren't exactly the easiest players to come back against)... :? more fortunate one against nalbandian !
he's so entertaining... i hope he manages to come back at the top. good luck, marcos !