Cologne boss Frank Schaefer has condemned supporters who made death threats against his team in the wake of their 4-1 defeat at Wolfsburg on Sunday.
A group of fans left a banner at the club's training ground on Monday which read: "If you go down we'll kill you.''
The Wolfsburg defeat left Cologne just three points above their opponents, who are third from bottom of the Bundesliga, with three games to go.
Schaefer, who leaves his post at the end of the season, admitted he was "shocked'' by the threat.
He told the Bild newspaper: "That has nothing to do with football, nothing to do with criticism. It is below the belt and destructive.''
Striker Lukas Podolski added: "This has nothing to do with common-sense. You can be disappointed, but such actions don't achieve anything. The people who have done this, they are no fans.''
Goalkeeper Michael Rensing branded the banner "a disgrace''. He said: "I hope, I think, that this is the opinion of the minority of our fans.''