Head coach Joachim Loew admitted Germany must improve if they are to challenge for the World Cup title after their fortuitous 1-0 win over Chile in a match which the visitors dominated.
Jorge Sampaoli's Chile, who face Australia, defending champions Spain and 2010 beaten finalists the Netherlands in Brazil, had the better of Loew's full-strength side in Wednesday's friendly.
Indeed the Germans endured a rare roasting at the hands of their fans who booed them off.
The hosts enjoyed only a brief period of pressure in the first-half which led to Mario Goetze's 16th-minute winner.
Chile were only denied an equaliser by the woodwork when Valencia's Eduardo Vargas clattered the crossbar with an hour gone and Germany goalkeeper Manuel Neuer well beaten.
"You could see just how strong Chile can play," said Loew, whose side face Portugal, Ghana and the USA at Brazil 2014.
"We had a lot of trouble breaking down their defence, it was incredibly difficult.
"We lost far too much possession and that gave us problems.
"Today we weren't in position to dominate the game and that is something we have to work on in the coming months."
Chile had the Germans under pressure for long spells and had 17 shots to the Germans' seven.
The corner count of Chile's 14 to Germany's four told its own tale.
"We go home a little sad," said Sampaoli.
"The result wasn't what we imagined, but the performance gives us many positive insights.
"We have shown that we can compete against one of the best teams.
"We were tactically very good, but unfortunately we did not score."
German captain Philipp Lahm said the crowd had every right to voice their disapproval.
"As Chile had so many chances, you can say we had a lucky win," he said.
"We have to accept the whistles and jeers, these people paid good money to watch us.
"We all know we still have work to do.
"But we always prepare well for a World Cup, so I am not worried."
In the match build-up, Loew had insisted "the clock is ticking" for his squad to prove their form 99 days before the World Cup starts.
But he has more questions than answers from his final friendly before naming his provisional World Cup squad on May 8.
"A win's a win, Chile were really good," said Germany's vice-captain Bastian Schweinsteiger.
"We didn't use our chances and we really have to improve but Chile are after all one of the best teams in South America."
But Arsenal centre-back Per Mertesacker took some positives from the win.
"When we slip into such an unorthodox way of playing, then we clearly have some work to do," he said.
"We should have countered quicker and we needed too much time to do that.
"It was a good lesson for us and it's not such a bad thing to keep our feet on the ground."