Wlad's not the greatest boxer to ever step in the ring, that being said, He'll be a million times more competitive than anything valuev has faced up to the point. Valuev's chin is by no means solid and i will go out on a limb and say that it is merely an illusion formed by his height that he can take a good punch (as he has never been hit by a good punch, especially since he has never fought a power puncher). Wlad's chin is suspect but valuev isn't exactly the worlds greatest ko artist as he is just a big guy who leans on people til they tire then he pushes them over.