Vitali couldn't will himself to go another 2 rounds in a title fight when he was ahead on all cards...he is not anywhere near as hard as Larry, don't even pretend he is.
This would be a very tough challenge for a prime Holmes. I could see Vitali winning it with his good jab that he uses to push his opponent back and his busy attack from the outside. Vitali's size would be sure to pose problems for Holmes. But with that being said though I'd expect Holmes to have a lot of trouble with Klitschko I still favor Holmes to pull out the decision. I think Klitschko would be leading through the half way point of the bout likely into about the 10th round. I think Klitschko would have some pretty clear cut rounds in his favor. But I'd expect Holmes to use his craftiness to slow some of the rounds down and edge them out. I see the late portions of the fight Holmes coming on and landing with some heavy shots likely getting Klitschko in trouble at a few points possibly even sending Klitschko who be tired and hurt to the canvas. I'd expect 1 or 2 real exciting rounds late in the fight with a surging Holmes getting the best of them. Overall I'd expect the late rally by Holmes to put him a head for a close but non controversial decision victory. If Holmes was anything but his best though going into a fight with Klitschko I think his title would be in serious jeopardy.