The 54-year-old feels there is still much more to come from his side, that hammered Portugal in the group stage, but says they will not simply sweep the African nation aside
The three-time champions are heavy favourites to overcome Vahid Halilhodzic's men, who surprised many by pipping Russia to second place in Group H.
However, while Low feels that there is still more to come from a Germany side that opened their World Cup campaign by routing Cristiano Ronaldo's Portugal, before then drawing with Ghana and edging out United States, he is not underestimating the threat posed by Algeria.
"Knockout games have a magic about them," he told reporters on Saturday. "We'll be full of confidence, but it would be a big mistake to think it will be easy.
"We've delivered so far. We're essentially happy, but we know that we can play better."
Meanwhile, Low revealed that Jerome Boateng will be fit to feature in Porto Alegre but added that the last 16 clash has come too soon for Lukas Podolski.
"Jerome has got a little niggle in his knee," the Germany boss explained. "But it won't rule him out of the Algeria game.
"Lukas will be missing for the last 16, though. He's pulled a muscle. He needs two to three days of rest."
Should Germany progress to the quarter-finals, they would meet the winners of France's clash with Nigeria.