Germany legend Franz Beckenbauer has admitted the defeat to Croatia left him 'stunned'.
The Euro 2008 pre-tournament favourites went down 2-1 in Klagenfurt to see their hopes of finishing top of Group B crushed.
Joachim Low's side looked a shadow of the team which bushed Poland aside so comfortably in their opening game as Croatia bossed the game for long periods.
Writing in his column in the Bild newspaper, Beckenbauer said: 'The same 11 which produced a rousing performance against Poland four days earlier was undone in such a way. I am stunned.
'In the 90 minutes against Croatia there was scarcely any of this glory left remaining.
'The team was ponderous, the positional play was wrong, we lacked bite. And the Croats have made an excellent impression on me.'
Germany still only need a draw in their final game against Austria to progress to the quarter-finals, where they will most likely face Portugal.
But Beckenbauer continued: 'I have seldom experienced how you can deliver such completely contrasting performances in such a short time.
'After the Poland victory I said 'Like that we have no one to fear'. After this defeat it is the opposite. Like that we have to fear Austria.'
Germany full-back Philipp Lahm, meanwhile, admitted the side have only themselves to blame for the shock loss.
And the Bayern Munich man knows they have to improve when they take on the co-hosts.
He said: 'We have all got to take a long, hard look at ourselves.
'We really, really struggled. We wanted to qualify today (Thursday), but there is still one game to go and we should not make everything out to be all bad.'