Borussia Dortmund captain Roman Weidenfeller has called for calm ahead of Tuesday's visit by Arsenal in the UEFA Champions League, after his side slumped to a shock 2-1 home defeat at the hands of Hertha Berlin.
Goals by Hertha's Brazilian striker Raffael and midfielder Peter Niemeyer put the guests 2-0 up before Dortmund's Poland striker Robert Lewandowski netted a late consolation goal in yesterday's German league match.
The result leaves the German champions in mid-table with two defeats from their opening five league games, with Arsene Wenger's Gunners set to open their Group F campaign at Dortmund's Signal Iduna Park next week.
"We need to remain calm and continue to build on our strengths: determined and compact defending after we have attacked. We need to fix the mistakes we are making," said Weidenfeller.
Coach Jurgen Klopp said his side endured a bad day at the office, while in London, Arsenal picked up their first Premier League win of the season at home to Swansea City thanks to an Andrey Arshavin goal.
"We could have built on a good first half, but too often we lost our calm in our passing game," said Dortmund's Klopp. "We played the ball three or four times to the feet of Hertha players.
"Hertha plugged any gaps in their defence like lightning and they deserved the win, we have to respect that. We can certainly play better and with more creativity.
"We had the feeling we could have attacked 100 times down the wings, but rarely through the middle. We have had so many great moments in this stadium, today wasn't so great - this can only help the development of this team."