They showed an interview with Andy as part of the coverage today. He looks good and seems very upbeat and positive. It always seems a good sign to me when he looks an interviewer in the eye, and he did.
Mayer could be tricky if Andy is off the boil, but if Andy comes out in the mood I think he'll be too strong for Mayer.
With respect, I don't know how much you can read in to Mayer beating Nadal last year. It is impressive, don't get me wrong, and it does show he has the ability to do it, though maybe not regularly enough to make a huge impact. Nadal often seems to tire at this end of the year though, and I can't really say that I blame him lol.
My prediction, Andy in straights if he comes out firing. Andy in three if he starts a bit slow. No pressure though Andy, you just do your thing.
That defeat to Mayer came just three matches after the trashing by Andy and he then didn't play again until the WTF, where he lost every match if I recall, including a 3&0 thrashing by Federer. He was clearly out of sorts.