Spain always have the capacity to play great one game and awful the next. Do you remember 1986? Denmark destroyed Uruguay 6-1 and looked like potential winners. Next game, Spain destroyed Denmark 5-1 and they then looked like potential winners - until they went out tamely in the next round.
They have only lost twice in over 2 years/50+ games. I think the game with Germany could be a classic. Far more open than
portugal or Paraguay who each put 9-10 men behind the ball and tried to stop Spain from playing. Germany won't play that way.
Having said that, I don't know if I want Spain to win. Germany are a pain in the arse because they ALWAYS do well and we talk about "German efficiency" and make it sound boring, but this German team is far from boring. They play good-looking football. Right now, they have been the best, most attractive team in the competition.
I couldn't see them scoring 4 against England, or again against Argentina, but they did and they deserved to. I am looking forward to seeing them play Spain and if they win that one, I will look forward to seeing them in the final against either of the other semi-finalists.
Definitely the best surprise for me is how well Germany has played and how much I have enjoyed watching them play. I for one will be cheering if they win the World Cup playing this way.