Joachim Low blamed a lack of defensive familiarity for Germany's frailties in their 4-2 defeat against Argentina.
The world champions were second best for long spells of Wednesday's friendly in Dusseldorf, in what was a rematch of July's World Cup final between the two sides.
Manchester United forward Angel di Maria ultimately stole the show this time around, claiming three assists and a goal to guide the South Americans to victory.
Germany had found themselves 4-0 down at one stage, but Andre Schurrle and Mario Gotze - who scored the winning goal in the World Cup final - added some respectability to the scoreline late on.
However, after the international retirements of several key players, such as Philipp Lahm, following the World Cup, Low conceded that a disjointed performance was largely due to the fact that a new-look team had yet to get to fully know each other.
"We've made some defensive mistakes and these errors were directly punished," he said. "Many of the players have never played together, and therefore you have to accept it."
Low is now keen to focus on Germany's opening Euro 2016 qualifier with Scotland in Dortmund on Sunday, adding "Sunday is the [start of] the European Championship [qualifiers] We have to win against Scotland."
Jerome Boateng could be back in the starting line-up for that clash after he missed out against Argentina through injury, although centre-back partner Mats Hummels is not expected to be fit enough to play.comments