USA's hopes rest much on Isner, assuming Bryans most likely win doubles. And I think even beating Almagro is difficult for him, let alone beating Ferrer who just had good US Open. And for Querrey that's even more difficult. I'd hope USA to get to final, but think Spain will most likely win, winning even one singles rubber will be difficult.
USA are in a strong position with the doubles, as per usual.
But they'll struggle to get a point out of the other four rubbers.
Almagro is an obvious target - at least for Isner anyway. Mucho has a dodgy shoulder, and has chucked in a few bizarre big-match performances on clay against unfancied big-hitters. Possible point there, but I do think Almagro will prevail.
Querrey is unlikely to be much of a factor this weekend, and I'll be shocked if Isner worries Ferrer too much.
I'll go with Spain 3-1.