Niko Kovac said he has never seen anything like Bayern Munich's 5-4 DFB-Pokal quarter-final defeat of Heidenheim but was unhappy with his side's lack of concentration.
Niklas Sule's red card after Leon Goretzka's early header opened the door for the second-tier side, who led at the break thanks to goals from Robert Glatzel and Marc Schnatterer.
Substitute Robert Lewandowski, who was deemed too ill to start, came off the bench at the break and set up Thomas Muller before putting Bayern in front, with Serge Gnabry extending the lead.
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But Heidenheim hit back against the 10 men once more, with Glatzel striking twice in three minutes to claim the match ball before Lewandowski's late penalty settled a breathless encounter.