Neil Lennon’s second reign as Celtic manager is over, with the defending champions trailing by points in the Scottish Premiership race.
There have been four league defeats, two of them to Rangers, who are way out in front and still unbeaten.
A fourth successive clean sweep of trophies was completed in December but the team that started 2021 with 15 domest ic wins and one draw to reach the Scottish Cup semi-finals and wrap up nine titles in a row in a truncated season has spiralled out of form to lose their stranglehold on success.
BBC Sport Scotland looks back at the pivotal matches in that fall from grace.
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Celtic 1-2 Ferencvaros, Champions League qualifier, 29 Aug
The Champions League was never going to be Celtic’s priority this season with the prize of a record 13 th consecutive league title on offer. But the least fans expect is a respectable showing.
This season’s format was different. One bad result and you were out, as Lennon learned the hard way.
The Scottish champions opened with a big win over KR Reykjavik but then suffered their earliest exit in 18 years after a shock defeat at home to Ferencvaros.
New goalkeeper Vasilios Barkas did not look too clever for Tokmac Nguen’s decisive breakaway goal, while the decision to use Ryan Christie as a makeshift striker in the absence of Odsonne Edouard raised a few eyebrows since Albian Ajeti and Patryk Klimala were on the bench.
Celtic 0-2 Rangers , Scottish Premiership, Celtic went into the first Old Firm derby of the season on the back of eight straight victories.
Both sides were unbeaten domestically but Rangers ran out comfortable winners at an empty Celtic Park as Connor Goldson exposed the defensive frailties that would become a recurring theme with both goals.
The hosts, without Edouard and Christie due to Covid – 23 cases on international duty and the injured James Forrest, failed to register a single shot on target in a passive performance, amid line-up leaks from inside the club.
Having been outplayed, Lennon said afterwards: “We have to roll our sleeves up and do better.”
It marked the start of a dismal run of just two wins in 12 outings.
Connor Goldson netted twice at Celtic Park in October Celtic 1-4 Sparta Prague, Europa League, 5 Nov
Despite being number one seeds, Celtic landed in a tough Europa League group and opened with a sobering home loss to a resurgent AC Milan on the back of that defeat by Rangers.
A draw away to Lille followed, leaving Lennon’s men looking for positive results against Sparta Prague to revive hopes of reaching the knockout round.