When Celtic signed Christopher Jullien from Toulouse for a reported £7m fee in June 2019, Neil Lennon and the club must have thought that they were signing a player who would be at the hearts of the Hoops defence for years.

Whilst that was the case in Jullien’s first season at the Hoops, three years later he finds himself well out of the first-team picture, and almost certain to leave the club before the end of the transfer window.

So where did it all go wrong for a player that could have been a Celtic mainstay for years, and why is he so far out of the first-team picture under Ange Postecoglou?

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Where it went wrong for the Frenchman can be traced back to the 30th of December 2020 when the Hoops took on Dundee United at Celtic Park. He and Celtic weren’t having the best of seasons, as the Hoops were trying to claw back a big Rangers advantage in the title race. 

The Hoops managed to defeat the Tannadice side 3-0 on the day, but the match was marred by a serious knee injury to Jullien, who collided with the post when clearing a ball off the goal line.

That freak injury, which occurred when Jullien was trying to stop the Hoops conceding a goal, kept the player out of action for 14 months, and by the time he made his Celtic return against Raith Rovers in the Scottish Cup under Ange Postecoglou, there were new first-choice defenders available for selection, and Jullien’s time as a first-team regular was over.

Why has Jullien not been a regular under Postecoglou? The injury has probably played a big part in that, as by the time Jullien was available for selection, the duo of Cameron Carter-Vickers and Carl Starfelt had made the centre-back slots in the side their own, and Postecoglou wouldn’t have wanted to break up a successful defensive partnership.

Jullien’s brief cameo against Raith is his only appearance under Postecoglou, and as he has not even made the squad for the Hoops first-team so far this season then his days at Celtic Park look numbered.

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When he does go Jullien’s time at Celtic can be split into two halves. The first was successful, with trophies won and big goals scored against Rangers and Lazio.

The second half was a disappointment, with injuries and not being in the manager’s plans. Despite that, when he leaves Jullien will receive best wishes from all at the club, but it is a bit of mystery the way his Celtic career has gone after such a bright start.