Euro 2024 hosts Germany lost 1-0 to Poland in a friendly in Warsaw on Friday, with Jakub Kiwor's first-half goal piling more pressure on coach Hansi Flick.
Poland's victory was just their second over their neighbours in 22 games dating back to 1933, and left Germany with a single win in four games since their disastrous World Cup campaign in Qatar.
Kiwor headed in a corner midway through the first half to give his side the lead against a disorganised Germany defence, adding to Flick's problems ahead of next year's Euro on home soil.
Despite the "totally disappointing result", Flick said his side had time to get things right.
"We're in a process and we're trying things out" Flick explained. "There's a long way to go until we'll get there."
"In June next year, we'll have a team that functions together."
Wingback Robin Gosens, who just six days ago played for Inter Milan as they lost the Champions League final to Man City 1-0, said his side wanted to get Germany "into a spirit of optimism and to get the country behind us."
"We know this can only be done through results, through victories."
Poland captain Robert Lewandowski, who won the Champions League with Bayern Munich under Flick in 2020, said "it wasn't perfect... we tried to make Germany's day difficult."
Under fire for continued experimentation with the team stuttering, Flick made nine changes from the team which drew 3-3 with Ukraine on Monday in Bremen.
Only captain Joshua Kimmich and centre-back Antonio Ruediger remained, with Flick handing 21-year-old central defender Malick Thiaw a debut as part of a back three.
