Shades of Jimmy Connors there!
Have just listened to an ESPN interview with Harrison in which he talks briefly about the match, giving a fairly mature measured assessment of the situation. Sounds confident and says that he's very glad to have the opportunity of playing Murray, adding "I know it'll take a lot to get things done" and that "I will have to stay within myself and trust myself".
Encouragingly, though, in an ESPN iterview with the pundits, Darren Cahill is saying that he's already noticed some positives in Murray even in the short time Lendl has been working with him, although he certainly isn't under-estimating Harrison or his potential.
So far Harrison hasn't claimed even a top 30 scalp, but he took a set off Soderling at the French Open last year and pushed Ferrer to five at Wimbledon. However, although Murray is bound to be nervous - all the top players tend to get a bit jittery at the beginning of Slams - and Harrison has nothing to lose, I'm sure Murray's experience, coupled with some of the "Lendl effect", will get him through this tough 1st round test.