Celtic manager Ange Postecoglou endured a rough debut season in the Champions League group stages as his side finished bottom of their table without a win in their six matches.

His team picked up two points in those games but he is not the first Hoops manager to struggle in Europe. Ronny Deila is another former boss of the Glasgow giants who failed to make his mark on the European stage.

Deila spent two seasons at the club and was unable to qualify for the Champions League in either of those campaigns, whilst he only won two of his 14 matches in charge in the Europa League in that time - failing to make it past the intermediate stage in that competition.

The Norweigan head coach could not crack that level of football with the club and some of his signings during his spell in Glasgow could have played a role in that.

One signing the manager dropped a howler on was the arrival of Nadir Ciftci from Premiership rivals Dundee United in the summer of 2015 for £1.5m.

There were warning signs for Celtic to heed as he was due to answer a charge of "excessive misconduct" as the Scottish FA accused him of biting an opposition player in a game against Dundee for his former club.

He was subsequently banned for eight domestic matches and did not appeal the decision, which meant that he started his Hoops career on the back foot.

Whilst he was banned from playing in the Premiership, he played six times in Champions League qualifiers and failed to score or assist a single goal.

Ciftci then came back from his ban to score four times in 11 league appearances, whilst registering zero goal contributions in three Europa League outings, and was loaned out to Eskisehirspor for the second half of the campaign.

The club eventually opted to cut his contract short by a year as they released him in the summer of 2018, after making just four appearances in Brendan Rodgers' time in Glasgow and spending time out on loan at Plymouth, Motherwell, and Pogon Szczecin.

Since departing Celtic Park, Ciftci has played for four different clubs in Turkey and spent six months at St. Johnstone back in Scotland earlier this year. At the time of writing, he is in the second tier of Greek football with Makedonikos - who he joined at the start of October 2022.

This shows that he has not gone on to prove Celtic wrong for allowing him to leave and has, instead, proven that Deila had a howler by deciding to sign him in the first place, as he is playing second-division football at the age of 30 - seven years after joining the Hoops for £1.5m.