[citation needed] In the following season Daum committed a mistake in the first round of the European Cup against Leeds United on 30 September 1992 by illegally putting in a fourth foreign player.

[6] The pressure grew when Bayern Munich manager Uli Hoeneß publicly claimed that the cocaine rumors against Daum were true.

Daum criticized the accusations of Hoeneß and parts of the press, and announced that he would prove his innocence with a hair sample.

Also, his agreement to become national team manager was annulled by the German Football Association on 21 October 2000, and Rudi Völler, the then interim coach, was given the formal job.

One year later, after a period out of the public eye and facing the prospect of jail time, Daum admitted he had used cocaine.

[8][9] As a result of the so-called Daum-Affair he was fired from Bayer Leverkusen and was unable to find a club to work within Germany.

While his failure to succeed in the Champions League was often criticised in the Turkish media, the improvements in Fenerbahçe under his management were significant.

At the end of the 2005–06 season Fenerbahçe lost the national championship to their arch-rival Galatasaray on the final week of the league, after which Daum resigned.

[14] On 22 March 2011, it was confirmed that Daum had signed a contract with Eintracht Frankfurt as coach after the club has sacked Michael Skibbe following a decline in the Bundesliga in the second half of season.

Daum took charge of just seven games and failed to manage a victory, his record of three draws and four defeats insufficient to beat the drop.

Following the end of the season, he asked Brugge to leave his position as head coach due to his family reasons and the club accepted his decision.

[21] On 7 July 2016, after two years of pause from coaching, Daum started his first experience at a national team after agreeing terms with Romania.

[22] It was reported that he signed a two-year contract which would automatically extend until 2020 if he managed to qualify the team to the 2018 FIFA World Cup.