Having suffered a Champions League hangover in Saturday's 2-1 Bundesliga defeat at rivals Schalke 04, Borussia Dortmund have apologised to their fans for a lacklustre first-half display in the Ruhr derby.
Last Wednesday, Dortmund reached the last eight of the Champions League with an impressive 3-0 victory at home to Shakhtar Donetsk in their last 16, second leg clash for a 5-2 aggregate win, but crashed four days later at Schalke.
Having been knocked out of the German Cup by Bayern after a 1-0 quarter-final defeat in Munich ten days ago, Dortmund lag 20 points behind in the Bundesliga with only a mathematical chance of winning a third straight league title.
They will find out their Champions League quarter-final opponents in Friday's draw, but Borussia's erratic Bundesliga form is a concern after their fifth league defeat of the season.
Having also lost by the same scoreline to Schalke at home in Dortmund last October, this is the first time since 2009/10 that Borussia have lost twice to their neighbours in the same season.
"We have to apologise to the fans for our first-half display," Dortmund's Germany defender Marcel Schmelzer told German Sky Sports.
"We lost again because in both games we didn't start with 100 percent passion and concentration.
"In recent matches, we have too often made the opponent look strong. This can't happen in such important games."
Borussia were left stunned at Gelsenkirchen's Veltins Arena as Schalke took a 2-0 lead with goals by midfielder Julian Draxler and Dutch striker Klaas-Jan Huntelaar before Dortmund's Robert Lewandowski pulled a goal back.
Centre-back Mats Hummels returned having missed the previous three matches with flu, but Dortmund were still punished for some poor defending.
At the same point last season, Borussia had conceded just 16 goals, but they leaked their 29th and 30th league goals of the season at Schalke.
"The team sat in the dressing room after the game like a picture of misery," admitted coach Jurgen Klopp.
"We allowed ourselves to be rushed and when that happens, simple things fall by the wayside."