I've felt all along that the Giro would probably be too much to overcome, and that he would get weaker, not stronger, as the race proceeds. But Bert seems to indicate it's all about the knee, and that it's getting better:
http://www.as.com/ciclismo/articulo/contador-ahora-todos-tienen-fatiga/20110714dasdascic_1/Tes
My knee was bothering me a lot so I'm satisfied with the result..I'm almost sure that it's getting better every day and with a little ice I will be ready for Saturday...My pedal stroke was not so good...hence I lacked power, but the others really burned themselves out today and that's in my favor.
He seems to be saying that since his knee prevented him from pedaling with full power, he did not exhaust himself that much and will be more rested than the others.
But for those of you who think it could all change with one great ride: Bert has won 6 GTs, but only two of them by large, convincing margins: this year’s Giro and the 2009 TDF. In the latter, though he won by more than four minutes over AS, most of that margin was made in TTs (team and individual).
He gained only slightly over one minute total on all the mountain stages.
To be fair, he did not try to drop AS on the final mountain stage, because with a large lead he didn’t have to do anything but stay with him. But on the previous mountain stage, when the race was still quite competitive, he tried to drop the brothers and couldn’t do it.
AFAIK, Bert has never taken as much as a minute out of Andy on any mountain stage they have raced, ever. That, I think, indicates as much as anything how difficult it will be for him to get back in the hunt, even forgetting Evans et al. Many people seem to think a completely healthy and fresh Bert could blow the race open on any one of the remaining three mountain stages. He might turn his situation around with a great ride, but I doubt very much he could blow the race open. He will almost certainly need two excellent MTF performances just to get the time differential down to where he could be fairly confident the remainder could be made up in the ITT.