The anger has subsided. The DVD has been analysed. But the hurt remains.
Crashing out of the Scottish Communities League Cup was always going to be a painful experience for Neil Lennon, who had set his sights on emulating Martin O'Neill and Jock Stein in negotiating the delivery of a Treble to Parkhead.
With Rangers unable to provide the major challenge as they prioritise getting out of Division Three, it appeared to be the perfect opportunity for Celtic.
However, as the history books will show, the manager's warning that just one bad day at the office coinciding with a cup-tie could end their dream proved to be prophetic.
Instead of emerging from the semi-final against St Mirren having taken another major stride towards the first piece of silverware of the campaign, Celtic took a major step backwards.
Memories of the bitter disappointment when they lost to Ross County in the Scottish Cup semi-final in April 2010, just a few weeks after Lennon took over from Tony Mowbray – whose reign, ironically, ended with a 4-0 defeat the last time St Mirren beat Celtic – came flooding back.
In the interim, the Hoops have made four winning appearances at Hampden, lifting the Scottish Cup in the process.
But they have also lost another three matches there, against Rangers, Kilmarnock and Hearts.
The current form run at the National Stadium reads, lost, lost, lost – and Lennon never rests easy when asked to carry the mantle of loser.
That message has been relayed, forcibly, to his players.
Initially, they were given the manager's take on how badly they had under-achieved as they prepared to shower and change after Sunday's game had ended 3-2.
Lennon's mood may have mellowed a bit by the time he got them back in for training yesterday.
But, again, they were left in no doubt that he will simply not accept standards being allowed to fall so far from the level he demands, and which he knows they are more than capable of maintaining.
The detailed analysis of the match has confirmed what Lennon and his management team saw live at Hampden, albeit through disbelieving eyes.
Home truths have been told, followed by a warning of what the repercussions will be if there is a repeat any time soon.
Now, Lennon wants to move on, acutely aware of the damage dwelling on such a disappointment could cause to a team which still has so much available to achieve this season.
The Treble has gone, allowed to slip from them in a manner which questioned whether the players really understand the significance attached to it by the supporters and their manager.
Atonement is now the objective, and the first step back into the good books has to begin tomorrow night when Kilmarnock – the side who began the hat-trick of Hoops Hampden horrors when they won the League Cup in March – come to Parkhead on SPL duty.
Lennon is reassured that playing again so soon after the weekend's disappointment is just what the doctor ordered to help everyone at the club relieve their misery.
The manager said: "It's probably the best thing you can do, to get back on the horse right away and go again.
"I will be looking for a really good reaction from the players, and I am sure the supporters will be as well."
The manager exonerated only Gary Hooper when he criticised his team's no-show at Hampden, and even the sought-after striker played well below the level which has seen his valuation soar in recent months.
So the fans will be very eager to see what personnel changes Lennon makes tomorrow.
It was a very strong team which took to the field against St Mirren as any complacency which existed did not emanate from the manager.
Lennon has learned the folly of being prone to knee-jerk reactions, but he will not hesitate to swing the axe if he believes it is what is required for the long-term good of the team.
"I will have a look at it," he said, when the subject of ringing the changes was broached.
"Some players might need a little break because that was three games in a week, and we have another two coming up over the next five days."
They start against Killie, then it's another knife-edge situation when Celtic travel to Kirkcaldy on Sunday to face Raith Rovers in the Scottish Cup.
The demands of international football follow this, and, of course, the up-coming Champions League tie against Juventus is looming larger by the day.
Lennon recognises the need to have everyone spot-on, mentally and physically, for the first leg on February 12, and said: "We are trying to keep them as fresh as we can, but it is not always possible."
The perception was that the mid-season break had done a lot towards achieving this, with the 4-1 win over Hearts and the 4-0 demolition of Dundee United confirming the well-being of his side when action resumed.
However, this is the business end of the season, and, as a consequence, the importance of any slip is magnified.
Lennon needs to play mind games with his players, and, to this end, he will swing between hammering them, as he did after Sunday's defeat, and building them back up, as he is doing ahead of tomorrow's game.
The objective is to get the very best out of every one of them in every game they are selected.
For a few more days only, the manager has access to the ultimate 'persuader', the threat of moving under-achievers out of the club, or replacing them with a new acquisition.
Lennon has suggested that, in the wake of this latest Hampden no-show, that's an avenue he may, reluctantly, have to revisit ahead of Thursday's deadline.
In truth, however, he knows he has the personnel required to achieve what he still wants them to achieve this season, and it will be a major surprise if there are any significant developments in terms of more players coming in before this window closes.
Lennon's priority remains retaining the talent he has at his disposal and he admitted: "I don't have an intention to do that (add more players), but Sunday has made me re-think things a little.
"I don't know where we go from that performance.
"I want to keep the players we have. If we can add to the squad we have, then so be it."