Germany slumped to an error-plagued 5-3 friendly defeat to Switzerland on Saturday, a worrying setback just two weeks out from Euro 2012 where they will be among the favourites.
The result illustrated just how much coach Joachim Loew relies on Bayern Munich expertise after eight of the club's players were left out of Saturday's squad to rest following their Champions League final defeat to Chelsea last weekend.
It was a first win for Switzerland, who failed to qualify for Euro 2012, over Germany since 1956.
Germany qualified for Euro 2012 without losing a match, but they have now lost two friendlies in succession having been defeated 2-1 by France in February.
Their last friendly will be against Israel on May 31 before embarking on their Euro campaign against Portugal, Netherlands and Denmark in Group B.
"We didn't expect a result like this and we cannot be satisfied by it," said Loew.
"After a lot of intensive training sessions, it's clear that we didn't concentrate enough and made a lot of mistakes. The team didn't function, we weren't good today.
"But despite that, there are still two weeks to go for us to work and improve. I am not worried."
Swiss coach Ottmar Hitzfeld, a former Bayern Munich boss, was overjoyed by the result.
"We played a sensational match. We found lots of gaps in the German defence and we were very efficient in front of goal. Germany seemed to tire quickly."
Saturday proved to be a nightmare for goalkeeper Ter Stegen who had a debut to forget with Swiss striker Eren Derdiyok, who has just left Bayer Leverkusen for fellow German Bundesliga side Hoffenheim, grabbing a hat-trick.
All three of his goals were set-up by passes from strike partner Tranquillo Barnettas.
Derdiyok hit the target twice in the space of three first-half minutes before central defender Mats Hummels pulled one back for Germany on the stroke of half-time with a header from a Mesut Ozil cross.
Derdiyok made it 3-1 on the 50-minute mark with Andre Schuerrle reducing the deficit 14 minutes later.
Andre Lichtsteiner made it 4-2 in the 67th minute before Marco Reus hit back for the Germans for 4-3 after 72 minutes.
Admir Mehmedi made it 5-3 for the home side just four minutes later as the goals continued to flow and it could have been six for the Swiss had Gelson Fernandes' 88th-minute header not come back off the post.