The Westphalians moved to the top of the Bundesliga table for the first time since May 2002 thanks to a 2-1 win in a stormy match at the Mungersdorfer Stadion.

But 90 minutes before the game started Dortmund found themselves under attack as they arrived at the ground.

"Some stupid idiot threw a stone at our coach from inside the woods before the game and then he ran away and celebrated with his friends," explained Klopp to Sky television.

"That was a cowardice and ridiculous thing to do. If anybody hears this person bragging about what he did in the pub tonight they should sort him out.

"But actually we should almost thank this idiot - what he did woke us up."

Dortmund gained revenge on the field, and for the matchwinner Nuri Sahin, the revenge was particularly sweet.

He had been ribbed by Cologne's Lukas Podolski during the game for Germany's 3-0 victory over Turkey seven days ago when both players were on opposite sides in Berlin.

After scoring the winner in the first minute of stoppage time, Sahin raced under the nose of Podolski to celebrate in front of him.

As Sahin revealed afterwards, the Germany international apologised to him for his comments after the game.

"We shook hands afterwards," revealed Sahin. "It was a very emotional game and a lot was at stake for both sides.

"We don't need to make a big issue out of what happened. When somebody comes to you after the game and apologises, then that deserves respect.

"We always got on well before the game and we will get on well in future too."

As a result of this latest defeat, which could see Cologne slip inside the bottom two this weekend, the pressure is mounting on their coach Zvonimir Soldo.

However, he praised his players for their performance, despite the final result.

"I cannot criticise my players in any way. Both teams had good chances and you just need a bit of luck in the end and we did not have that today.

"Dortmund had the luck, but I still think my team would have deserved a point."