BERLIN: Germany take on Ireland in Friday's World Cup qualifier with questions needed answering over the guests' defence and a lack of strength in depth in the German back-four being blamed.

Germany coach Joachim Loew is without centre-back Mats Hummels, who has a bruised foot, while captain Philipp Lahm is suspended for the match at Dublin's Aviva Stadium with the Irish having said they want to test their guests' back four.

In Lahm's absence, Germany midfielder Bastian Schweinsteiger will take over the captain's armband, but the Germans have admitted the defence needs tightening as a matter of urgency.

“It is a problem that has been following us around for some time,” said German assistant coach Hansi Flick.

“We simply don't have the bulk of players that we want.

“We're focusing on the defensive work and the basics, because we have seen that recently they were not always up to scratch.”

In his six years as head coach, Loew has used 23 players on the left or right side of defence with his captain Lahm as the only name who has remained throughout.

Bayern Munich defender Jerome Boateng is expected to play on the right against Ireland with Dortmund's Marcel Schmelzer on the left with Arsenal's Per Mertesacker at centre-back alongside Bayern's Holger Badstuber.

The Irish have already said they hope to cause the Germans defence problems, according to Ireland's assistant coach Marco Tardelli.

Plenty of holes were exposed in Germany's defence in the 3-1 friendly defeat by Argentina in August, while Austria could and should have sneaked a late equaliser in their 2-1 defeat in Vienna to the Germans last month.

Germany last faced Ireland in Dublin in 2007 when a goalless draw was enough to book the Germans' place at Euro 2008.

“They are an difficult opponent to play against with crazy fans,” said Germany's Arsenal striker Lukas Podolski with the Irish having enjoyed the last of their five wins over the Germans back in 1994.

“We want to go there and take the three points, we have the necessary quality to beat them.”