Borussia Dortmund's inability to defend aerial passes laid the foundations for their resounding 5-1 defeat against Bayern Munich in Der Klassiker on Sunday, according to coach Thomas Tuchel.
Second-placed Dortmund slipped seven points off leaders Bayern as braces from Thomas Muller and Robert Lewandowski as well as a late Mario Gotze strike ensured the champions a dominant victory at the Allianz Arena.
Pierre-Emerick Aubameyang got Dortmund's only goal before the break as Tuchel's men lost for the first time since his appointment.
However, it was the lofted Jerome Boateng assists for two of Bayern's goals that caused Tuchel the most frustration, as Dortmund were the architects of their own downfall.
"At the beginning we were brave but goals from long balls are the most bitter that you can get. It must not happen," he told Sky Deutschland.
"We weren't as clinical in the final third as Bayern but what can I say? That sort of thing [long balls] shouldn't happen.
"We need to go back to defensive positioning and discipline."
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