Germany crushed the Argentines 4-0 in the last eight after stifling their playmaker Lionel Messi but Low said European champions Spain were a completely different proposition.
"They are the country with the greatest consistency for the past two to three years," the 50-year-old told reporters ahead of Wednesday's showdown in Durban.
"Spain do not have one Messi. They have more than one Messi. Especially in attack there are many players who can decide a game. Spain are not like England and Argentina, teams that make mistakes," added Low.
"They make very few mistakes in offence or defence so we have to force them to make those mistakes."
"Spain's midfield has a well-oiled axis with Iniesta and Xavi. But (Germany's) Sami Khedira and (Bastian) Schweinsteiger are good as well so there will be a key situation there to carve out advantages."
The coach's only injury real concern is striker Cacau, a possible replacement for Muller. Low said he could also opt to play Toni Kroos or even Piotr Trochowski in his place.
Spain coach Vicente del Bosque and his players have expressed their admiration for Germany, praising Low's success in building a side out of exciting new talent mixed with experienced campaigners.
"We know we are on the verge of realising something that is the dream of any child, or any player," goalkeeper Pepe Reina told a news conference on Monday.
"Just two more matches now, we are very close."
