I read the news about the injuries which forced Justin Henin to rest and forgo all the remaining matches in 2010! That's pretty sad for her I guess. I'm not sure why some of them (including herself) who announced the retirement much earlier but come back to join the matches again. Nothing is wrong literally but result showed that they are not as competitive as before so that's the disadvantage for themselves. I bet they do not train themselves as hard during their prime time and the flow in them just not be the same... Like the former 7th time champion Michael Schumacher, I think he's too passionate in F1. He couldn't stop himself for not racing in the circuit after some years of retirement. But he failed to make a remarkable one now!