The Bundesliga tie between Cologne and FC Mainz was postponed this afternoon due to an "accident", although reports in Germany suggest that the referee tried to commit suicide.
The club issued a statement saying the match was called off because Babak Rafati was unable to take charge of the fixture.
"A replacement is not available in the short-term," the statement added.
Reports in the German media have claimed that Rafati was found in his hotel room having attempted to take his own life.
Cologne's chairman Claus Horstmann was quoted in Bild as saying that "[Rafati] is alive".