If he plays anything like he did today, then he will win in straight sets (although Chela looked very good against Djokovic last week)
I actually see Chela winning a set here, as I can see him being able to either stick with Murray for a set, Murray have a breakdown and some point and go walkabout for enough time for Chela to get a break, or he plays too passively for a while and plays to Chela's strengths
Murray is 3 for me though, with him running away with the 3rd
They have played 3 times before, the H2H is 2-1 in Andy's favour.
I think this is Andy's match to win or lose. If he plays like he did today (not exactly, of course, Chela is not a serve-and-volleyer like Stepanek!) he will win.
Today after the first set, I was shouting at the monitor, "Concentrate!" I'll try that tactic again tomorrow