Unknown player. Must be ace on river, which I don't like (yes, because he can hava nut flush draw from flop) and I should small block bet here or easy check-fold how here?

Unknown player. Must be ace on river, which I don't like (yes, because he can hava nut flush draw from flop) and I should small block bet here or easy check-fold how here?

Seems alright to fold the river. You could bet 1/3 pot and fold to a raise, but not sure villain would call with worse if you would do that.
Cheers,
SDK1987
I think b/f and x/f are both fine here. Against unknown, I don't expect them to turn a pocket into a bluff - those hands will just check behind. I'm a bit afraid of a missed diamond draw bluffing us out of the pot, but I think that this doesn't happen often enough to justify a call.