Borussia Dortmund coach Jurgen Klopp has put his defenders on alert after Sunday's 1-1 draw with Borussia Monchengladbach, warning they must improve or risk elimination from the German Cup this week.
Dortmund face Bayern Munich in the quarter-finals of the competition on Wednesday night and Klopp believes the defensive effort in the Bundesliga stalemate provides him with some concerns.
Monchengladbach's equaliser came in questionable circumstances after appeals for offside were waved away, but Klopp preferred to focus on the woes of Dortmund's defence, claiming errors will be unacceptable against the current league leaders.
"Offside calls have become a part of footballing folklore," he said. "Instead of clearing the danger, we got caught out, and then the ball deflected twice to add more insult to the injury.
"This [match against Bayern] is a totally different game. Today we had quite a lot of possession, especially in the first half. That will not be our problem on Wednesday. We have to defend properly in Munich and take the opportunities that we get.
"Gladbach hurt us every year and did so again today, although they defended unpleasantly. We were initially dominant but our grip on the match began to lessen and Gladbach then emerged. There are worse things than a draw here, but we are not very happy.
"I am not filled with satisfaction, but we put in a really good away performance for over an hour. (But) the game intensified after half-time as Mats Hummels could not continue."
Klopp's hopes of recruiting in the summer look to have been given a boost, with Dortmund chief executive Hans-Joachin Watzke revealing the club is in a comfortable position financially.
But Watzke insists a summer spending spree is not on the cards as the club aims for a debt-free season.
"I hope that for the full year we manage to make more than €250m [£217m] for the first time," he said. "So far in the Bundesliga, Bayern are the only club to record figures that substantial. In 2005, when I arrived at the club, the figure was just €87 million [£75m].
"To have no debt is our goal. We strive for maximum sporting success, but we do not spend more money than we are taking in."