"The mixture is not ideal at the moment," said Kahn, who captained Germany to their 2002 World Cup final defeat to Brazil.
"There needs to be a better balance between the forwards and the creative players like Mesut Ozil. "When you invest too much in attack, looking to find combinations and players in space, you don't always get into good scoring positions."
Matthaeus, who holds the record of 25 World Cup appearances, said Germany's problems begin in defence as centre-backs Benedikt Hoewedes and Jerome Boateng have been used mainly as wing backs at the World Cup.
Germany needed late goals from Andre Schuerrle and Ozil to edge a 2-1 extra-time win over Algeria in Porto Alegre on Monday and book their date against France at Rio de Janeiro's Maracana stadium.
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But Kahn says the poor performance against Algeria could act as a catalyst with Germany chasing a fourth World Cup title.
"Sometimes such a negative match in the last 16 can have a healing effect for the next matches," said the 45-year-old.
The Germans are making no excuses for grinding out a win over the North Africans by adopting a 'winning ugly' mentality.
Only an outstanding performance from goalkeeper Manuel Neuer kept Algeria out before replacement Abdelmoumene Djabou netted a consolation goal just before the whistle.