Calzaghe by UD, he won't knock him out. Only worry if that Calzaghe believes the hype, when he beat Lacy he was in the perfect frame of mind, he was being knocked by everyone as a dodger and had something to prove big time. He was also very aware that Lacy was dangerous, so he had a bit of that fear factor keeping him focused and on his toes.
If he is fighting Johnson I'd be very impressed, after all the speculation that he'd fight a 'tune up' he's arguably facing one of the biggest challenges out there, certainly a bigger challenge than Beyer and as tough if not tougher than Kessler.

Let's just hope also that JC makes the weight properly, not just by doing less conditioning.