Two more matches to go for all. I think Nishi is pretty much done at this point. He had a couple of very good back to back win. He will have to bring his best against Nole, who seems to be fresher of the two at this point. Andy didn't push him enough, didn't take it to 3rd set. So he is relatively fresh.
Berdych too is relatively fresh. Not sure though if he's going to give his all in his next match. Hasn't seen a win against Nadal since 2006 but still, there's always a first time.