So how can a team defeat the beast that is Barcelona but fail to overcome an Inverness side who one week earlier were walloped 5-1 on their own turf?
That’s the question the Celtic support were struggling to come up with an answer to after watching their team meekly go down 1-0 to Inverness Caley Thistle on Saturday.
The memories of that incredible night at Celtic Park when goals from Victor Wanyama and Tony Watt sent the Catalans home empty handed seemed a lifetime ago for the Hoops faithful as Billy Mckay’s 64th minute strike was enough to sink the SPL leaders and secure a massive three points for Terry Butcher’s men.
In February 2000 a famous Scottish Cup defeat to the Highlanders was the final nail in the coffin of John Barnes’ short lived tenure as Celtic boss and just under 13 years later another victory for the men from the north in Glasgow’s east end prompted current Celts gaffer Neil Lennon to raise a question over his own future.
After watching his side produce an inept, below par performance Lennon, who had a verbal altercation with one of his own fans cut a frustrated figure threatening to walk away.
He said: “They are frustrated. I disagreed with them, I didn't like what they said about the team. Look, if they are not happy with what I am doing and they want me to go, I will.
"Look, if they are not happy with what I am doing and they want me to go, I will.
"I can't repeat it (what fans said) because it is public arena but there were a lot of expletives and heavy criticism, which I didn't think was justified and there was a lack of patience with the team as well.
"If there was a lack of application and commitment I would be the first to criticise the team. I didn't see that but I did see a lack of composure and quality in the final third and that's what cost us.
"If I think it is justified then I don't have a problem with it but I don't think it was justified today. But they pay their money, they are allowed to say what they like. I've got my opinions on it and sometimes I give them as well.
"I am not happy with the league form, it is my team at the end of the day so I take the responsibility for it. It's not for the lack of trying to find the answers."
Lennon’s words are dynamite, perhaps said in the heat of the moment but said nonetheless.
With a League Championship and a Scottish Cup win under his belt along with qualification from their tough Champions League group a distinct possibility you would assume Lennon would be comfortable in his position but an undercurrent of unsatisfaction over some of his managerial decisions can be sensed amongst the Celtic support.
Since taking over the mantle of the Celtic hotseat from Tony Mowbray in April 2010 Lennon has overseen a side which were dumped out of the Scottish Cup to Ross County, humbling European defeats to Braga and AZ Alkmaar and League Cup final losses to both Rangers and Kilmarnock.
Those that questioned whether the absence of Rangers from the top flight would prove to be detrimental to the showings of Celtic this term, including this observer, appear also to have been proven correct.
An SPL win ratio this season of only 50% is certainly evidence that the sharpness and urgency required is missing from this Celtic team and if there are to be fingers of blame pointed in the direction of the underperforming players then perhaps it is worth considering that these are players that Neil Lennon has assembled and it is he who must take the responsibility for the current failures of the Parkhead outfit.
His handling of Scott Brown too appears to be debatable.
The Celtic skipper requires an operation for an ongoing hernia problem which leaves the 27 year old feeling like a pensioner after matches but Lennon continues to send him out onto the field of play, something Brown apparently requests.
That’s poor man management in anyone’s book and something else Lennon’s critics can use to undermine him.
Neil Lennon, just like his opposite number in the other end if the city Ally McCoist, can consider himself extremely fortunate he holds the managerial reigns at such a massive club as the old firm no longer can push the boat out and land top dollar bosses who wish top dollars to produce high quality sides.
But whilst he holds the keys to the managers office at Celtic Park Neil Lennon must accept he has to up his game and getting involved in shouting matches with his own fans will not help but only hinder his prospects of going down in history as one of the better bosses of the 125 year old club.