Talking Point: Why can't Celtic win at home after European matches?
Neil Lennon's side failed to win at home for the third successive match after a European tie.
For the third time in three matches, Celtic came off the back of a Champions League tie and failed to win at home on their return to SPL business this weekend.
Inverness Caledonian Thistle benefited from the failure of Neil Lennon's side to convert their chances, with Billy McKay's goal ensuring the visitors' first league victory at Celtic Park.
Celtic had 11 chances on Antonio Reguero's goal on Saturday, but managed just three shots on target in a wasteful afternoon in front of their home crowd.
Kilmarnock were victorious in the east end of Glasgow after Barcelona secured a last gasp win at Camp Nou over Celtic.
St Johnstone then also profited from post-European blues, getting a draw on their travels days after the league champions shocked Barcelona with a win in Scotland.
What is to blame? Are Celtic failing to cope with expectation to walk this season's league? Are they struggling to adapt from being under the cosh in Europe to having to dominate league opponents? Or is it all a red herring caused by fatigue, which will balance itself out over the course of the campaign?