IT IS one of the constants which underpins this ever-changing game.

Any time Celtic lose, an inquest is required.

It doesn't matter if it is going down 2-0 to AC Milan at the San Siro in the Champions League, or crashing out of the Scottish League Cup to Morton at the third round.

Even conceding a late goal to St Johnstone in the match which split the aforementioned, causing a cruise of an Premiership game to end in unnecessary anxiety, sparked a post-mortem for which would have done Quincy proud.

How? Why? Who's to blame?

Opinions abound, but only one matters - the one belonging to manager Neil Lennon, who must come up with the definitive answers.

Despite the fact Celtic have no God-given right to win any game, many of their fans still believe they should never lose one.

When they do, especially against a team from the Championship in a home cup tie, spleens are vented on message boards, phone-ins and on social networking sites where anonymity is often used as a shield against the need for justification.

Between now and Saturday's lunchtime kick-off at Kilmarnock, what went wrong against Morton, who was at fault, and who should never play for the club again are sure to get a continuous airing.

Twelve years after first walking in the door at Parkhead, Lennon knows to expect this, and, more importantly, how to keep it in context.

The fact no-one will be hurting more than him as he sifts through the ashes of another League Cup campaign which has gone up in smoke does not matter to those throwing the brickbats.

Lennon accepts he is paid to make the team successful. As a predecessor, Gordon Strachan, was known to say, you are not paid to be the manager of the club, but to deal with all the stuff that goes with it.

This is just such a situation, and a calm, measured approach to getting everything back on an even keel is the immediate task facing the current Celtic boss.

He has no time to dwell on what happened on Tuesday, other than to ensure the players involved recognise it is simply not acceptable to go out of a competition in such a poor fashion.

The stats confirmed they had more than enough possession and chances to win several cup ties.

So, to see any opportunity of landing the club's first treble since 2001 slip away at such an early stage of the campaign has to be deemed hugely disappointing.

It turns the spotlight on the men brought in for the match as a handful of those Lennon considers have been stalwarts so far this season were given a well-earned night off.

The line-ups against Milan and against Morton were, like the strength of opposition, very different.

But the common denominator in the matches was that Celtic failed to find the net.

Unsurprisingly, that leads many to ask how different it might have been had the Hoops managed to hold on to the top scorer for the previous three seasons, Gary Hooper.

It really is a question without foundation as the striker, pictured left, made it abundantly clear he wanted to return to England, and the money offered by Norwich for a man in the final year of a contract he refused to renew made it a good piece of business by Celtic.

Ironically, Hooper chose the very night his old club were failing to find the net against Morton to start scoring for the Canaries as they came back from 2-0 down against lower-league opposition, Watford, in the English version of the League Cup.

Hooper scored the equaliser, then, in extra time, knocked in the winner in what was his first start for the Barclays Premier League side.

Injury prevented him getting the chance to play for Chris Hughton's team until last weekend when he made an appearance as a sub against Aston Villa.

But as Lennon predicted, he has already proved he is good enough to get goals back in his homeland.

And new team-mate, former Rangers and Hibs defender, Steven Whittaker, believes the 25-year-old has already shown how good players adapt and answered the Norwich fans who wondered why they needed another striker after bringing in Ricky van Wolfswinkel from Sporting Lisbon.

"It is going to be tougher, and the chances might not come around for Gary as regularly as they did at Celtic," said the Scotland full- back. "But Gary has got the quality to come alive when the ball is in the box.

"It's up to the rest of us to supply the chances. If we can create around about him, hopefully, he will be the man who can get the goals."

There may not be any Champions League action to stretch Hooper, but the challenge of competing against top-level defenders every week in the Premier League will ensure his development is not arrested.

It is a culture shock to go from a team where you are expected to win very game, with serious questions asked if you don't, to one where, at the start of every campaign, survival is the name of the game.

But Whittaker is confident refusing to give up pursuit of Hooper shows there is more than enough ambition being shown by Norwich to ensure the hitman's appetite for big-game action is satisfied.

He said: "The club have only been back in the Premier League for two seasons and have finished 12th and 11th.

"We want to keep on progressing and trying to better what we have already achieved. The manager has made some good signings, and, hopefully, we can gel together quickly."

A sentiment echoed by Lennon at Parkhead where the likes of Teemu Pukki, Amido Balde and Derk Boerrigter have been acquired in an attempt to keep Celtic's goals flowing.

The transition - even with Anthony Stokes stepping into the void with four already - has not been seamless, and neither was it expected to be.

But it is worth considering that in the 14 games played this season, a total of 21 goals have been scored, with blanks in matches against Elfsborg, Shakhter Karagandy, Milan and Morton.

In their first 14 games last term, they had hit 28 and Hooper had scored nine of them - four in the League Cup against Raith.

Replacing No.88 remains Celtic's No.1 priority.