Cologne came from behind to deal Borussia Dortmund's title hopes a blow with a 2-1 win at the Mungersdorferstadion.
Sokratis Papastathopoulos headed Dortmund in front as Thomas Tuchel's men dominated, but they failed to add a second and were punished in the second half.
Simon Zoller crowned a sustained period of Cologne pressure by bringing them level before Anthony Modeste netted the winner in the last minute, denying Dortmund a point and seeing them slip eight points behind Bayern Munich at the top of the Bundesliga.
Dortmund were already leading in the possession stakes, with more than 70 percent, when they took the lead in the game with Papastathopoulos heading in Henrikh Mkhitaryan's corner.
Frederik Sorensen's header deflected off Mats Hummels, but Roman Burki turned the ball around the post instinctively as the hosts almost scrambled an unlikely equaliser.
It was a different story in the second half, however. Gone was Dortmund's control, and in came Cologne's courage.
Yannick Gerhardt's shot was turned onto the post by the fingertips of Burki with the effort rousing the home fans, who suddenly believed there could still be something in the game for their side.
Their belief was not misplaced either with Zoller capitalising on a defensive mistake and placing his shot past Burki to bring Cologne level with 15 minutes remaining.
There was still time for Cologne to seek -- and find -- a winner.
Modeste broke a 682-minute goalscoring drought in the final minute of the game, turning in Sorensen's header from deep with a sweeping volley past Burki to earn the Goats all three points.