Celtic have had better weeks, that's for sure. They followed up a 3-0 loss to their rivals in the League Cup with a sobering 3-1 defeat to Ferencvaros at Parkhead in the Europa League.

Martin O'Neill's side did not appear to learn any lessons from their dismal loss at Ibrox ahead of welcoming the Hungarian outfit to Glasgow, as they looked far too open defensively throughout the game.

Former Hoops loanee Daniel Arzani, an Australia international, was one of the stars of the show for the away side, scoring one of their three goals.

Meanwhile, O'Neill's current forward players looked devoid of quality when they got into positions in the final third, and Sebastian Tounekti was one of the players who struggled.

Why Sebastian Tounekti is Celtic's most frustrating player

The Tunisia international is the most frustrating player in the current Celtic squad because he often does the hardest part, getting into dangerous positions, but he lacks the final action.

There was a moment in the second half when Celtic were applying pressure to get back into the match and Tounekti beat his man inside and out with a brilliant bit of skill, running into the box with a clear sight of goal, and he fired an aimless shot straight at the goalkeeper.

The £5m signing from Hammarby has all the skill in the world when he is dribbling at defenders, completing 71 dribbles since the start of last season, but his lack of end product means that he is not effective enough on the flank.

Since the start of last season, Tounekti has completed more dribbles than he has produced key passes and shots on target combined, which shows that he is spending far too much time on the build-up instead of focusing on delivering quality in front of goal.

On the evidence currently available, the 24-year-old winger has been a flop at Parkhead because of how frustrating his attacking play has been for Brendan Rodgers, Wilfried Nancy and, now, O'Neill.

£11m wasted: Celtic had a bigger flop than Sebastian Tounekti

Tounekti, however, is not the biggest waste of money or even the biggest attacking flop to have been signed by the Scottish Premiership giants in recent seasons.

In the summer of 2024, Celtic decided to splash a fee of up to £9.5m on the permanent signing of Adam Idah after a brief loan spell at Parkhead in the second half of the 2023/24 campaign.

The Ireland international had shown promise during his loan stint, scoring nine goals in 19 appearances, and that convinced Rodgers to snap him up permanently for a mammoth fee, which currently sits at the third-most expensive fee ever paid by the club.

Unfortunately, the signing did not go to plan for anyone involved and that £9.5m ended up being money down the drain, because he did not last long in Glasgow.

Idah was tasked with replacing Kyogo Furuhashi as the new long-term number nine at Parkhead, as the Japan international went on to sign for Rennes for £10m in January 2025, but he failed to show the quality required to fulfill that role.

The Irishman was given plenty of chances to show that he had what it took to lead the line for the Hoops week-in-week-out in the Premiership, and did not step up to the mark.

A return of 22 'big chances' missed and only 13 goals in his time as a permanent Celtic player in the league shows that the £9.5m forward was far too wasteful in front of goal.

Idah reportedly earned roughly £1.6m in wages during the 2024/25 campaign. That meant that the Hoops essentially paid just over £11m for the striker's talents that season, given the £9.5m fee that was paid to Norwich, and his output did not justify that expense.

Tounekti, who only cost £5m from Hammarby, has not been as big of a flop as Idah was because he has not been as expensive of a mistake for the Scottish giants.

Celtic paid one of the most expensive fees in their entire history to sign the Irishman from Norwich to be their long-term number nine, yet they then decided to cash in on him after one season at Parkhead.

Swansea City signed the forward for a fee of £6m in the summer of 2025. Whilst the Hoops recouped a bit of their money back, they still spent over £11m in an attempt to fill their number nine role, and that money was ultimately wasted.