Late drama ensued at the RheinEnergieStadion as Anthony Modeste's last-minute strike helped Cologne come from a goal down to beat Borussia Dortmund 2-1 in the Bundesliga on Saturday.
Cologne fell behind to Sokratis Papastathopoulos' 18th-minute header as Dortmund made the most of their early pressure.
But the hosts responded brilliantly and Frederik Sorensen saw a header well saved by Roman Burki, while Yannick Gerhardt struck the post.
It appeared as though Dortmund would see out the pressure until Simon Zoller capitalised on Burki's poor clearance to lash home the equaliser in the 83rd minute.
And there was time for more drama as Modeste came off the bench to emphatically score his first goal since October 4, sending the home fans into delirium.
The late collapse means Thomas Tuchel's Dortmund now trail leaders Bayern Munich by eight points heading into the mid-season break.
There was no sign that Dortmund would struggle in the early stages and they broke the deadlock in the 18th minute when Cologne switched off at a corner and Sokratis met Henrikh Mkhitaryan's delivery with a thumping header into the bottom right-hand corner.
The goal seemed to spark Cologne into life and two dangerous Marcel Risse deliveries from the right failed to pick out a team-mate.
And Dortmund were thankful to Burki when Jonas Hector's dangerous free-kick was met by Sorensen's downward header, but the goalkeeper flung himself low to make a brilliant save.
Referee Knut Kircher then waved away Cologne protests for a penalty when Pawel Olkowski went to ground under Park Joo-ho's challenge.
Dortmund made two changes at the break with Park and Mats Hummels replaced by Marcel Schmelzer and Sven Bender.
But it was Cologne that continued to impress and Dusan Svento dragged a half-volley wide when the ball fell kindly in the area from a corner.
At the other end Shinji Kagawa wasted a great chance to extend Dortmund's lead. Bender's clipped cross picked out the Japanese, who headed tamely wide from eight yards when unmarked.
The end-to-end nature of the match continued as first Zoller saw a goal-bound effort deflected over the crossbar for Cologne, before Sorensen made a fine block after Jonas Hofmann had danced his way past a couple of challenges.
With the clock winding down, Burki again came to the rescue for Dortmund. The space opened for Gerhardt and his shot was tipped onto the post by the goalkeeper.
But Cologne did get their deserved equaliser seven minutes from time. Burki and Bender made a mess of things at the back and Zoller stole in ahead of the defender to emphatically hammer home to the delight of the home supporters.
It was not yet over, though, and Cologne were celebrating a brilliant comeback in the 90th minute.
Sorensen's header sailed over Dortmund's defence and Modeste struck a brilliant first-time drive past Burki into the bottom left-hand corner.
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