The Germans, who crushed Ireland 6-1 in Dublin on Friday with in-form winger Marco Reus scoring twice, have nine points after winning their first three Group C qualifiers.
Sweden also have a perfect record and are second with six points from two games, but Reus was left scratching his head when asked by reporters on Sunday to name any of the Scandinavian country's defenders.
"Ah, is Olof Mellberg there, has he retired?" Reus said in a reference to Sweden's former captain who ended his international career after Euro 2012. "Honestly I do not know. I have not dealt with that yet."
Germany's team spokesman quickly came to Reus's rescue saying: "The team discussion has not yet taken place."
"It will be a tough job against an opponent who is organised, tactically clever and has an outstanding striker in Ibrahimovic. It is our toughest rival in our group," Lahm told reporters.
"We have to be able to withstand that pressure, break forward very quickly. He is the complete striker, the complete package. If we allow few chances at the back then we will win."
"We are focused. We take every game very seriously. That is what we are doing. We know what's at stake," said Lahm.
"My scout has told me the Germans played fantastically," said Sweden's coach Erik Hamren. "It will be a wonderful challenge. We have to be physically strong, both in one-on-ones and in running."
