THE first competitive goal of Martin O'Neill's career at Celtic was scored by Henrik Larsson in a win at Tannadice.
The first of Gordon Strachan's time in charge was converted by John Hartson. The first of Tony Mowbray's reign was buried by Scott McDonald. When Neil Lennon took over, the first man to find the net for him was Robbie Keane.
Larsson, Hartson, McDonald, Keane. A familiar quartet, all with their contributions to Celtic's modern history, and four men who each reveal something about where the club stood when they were there.
Larsson represented O'Neill and Celtic at their richest. Belts were tightened under Strachan but he still inherited a £6m man like Hartson. McDonald reflected the club's downsizing, a striker who delivered an outstanding return and did so for a much smaller transfer fee and salary. Keane may seem like a return to a higher financial commitment but he was, of course, only at Celtic on loan.
Callum McGregor is in illustrious company, then. Another Celtic manager has his first goalscorer and McGregor is as unlikely as they come. The 21-year-old bubbled with infectious enthusiasm after delivering Celtic's 1-0 Champions League qualifying victory in Iceland on Tuesday night.
"That was the biggest goal of my career," said the endearing young Glaswegian, although that sort of went without saying given that the game against KR Reykjavik was his competitive Celtic debut.
It would be premature and unfair to hold McGregor up as some sort of symbol of what Deila intends to do with Celtic, or to start pontificating on how this manager will give youth more of a chance than his predecessors did.
Young players come and go at a club the size of Celtic. For every one who makes it, another two or three retreat from the first team squad and are quietly moved out. Rather than burden McGregor with silly expectations, it will suffice for now to acknowledge how well he has worked in the opening weeks of Deila's management, presenting a case for inclusion the other night which the new manager found irresistible.
McGregor, neat and sharp on the ball, was not even playing in his usual position. He normally operates in central midfield, playing in Kris Commons's area, and scored 14 times there in 40 loan appearances for Notts County last season.
Deila played him on the left in Iceland because he wanted the experience and quality of Charlie Mulgrew and Stefan Johansen at the hub of his midfield. McGregor was thrilled to be involved, naturally, and he wasn't the only man asked to perform in a slightly unfamiliar place. Johansen played on the right of centre whereas last season he was on the left. Leigh Griffiths was asked to play wide on the right of the three behind Anthony Stokes (and was not involved in the match as much as Celtic would have liked).
It will be a few months until any significant football judgments can be made on Deila and results will shape his credibility and reputation. So far, all that can be said is that he continues to be quietly impressive.
He is measured and confident in his comments and there is a sense of steeliness about him. Tuesday night was a significant result for him and while he praised the overall performance, and McGregor's display, he could not be accused of gushing over it all. On McGregor he said: "He has big talent but I want him to be more direct, to be more forward and link up more with the full-back".
On whether the lad had a big future at Celtic, he avoided easy platitudes and replied: "I never talk so much of the future. People have to develop, that's what I've said all the time. If people get better they can stay, if they never get better then they have a problem . . . and I have a problem." On the whole team's goalless opening 45 minutes against the Icelandic part-timers: "The first half was sleepy for me. It was sideways passing. I hate too much sideways play."
There is no sideways movement from Celtic in the Champions League for the time being. They are moving directly forward.
Taking a 0-0 first leg result to the return fixture at Murrayfield on Tuesday would have been deeply uncomfortable, but McGregor's unanswered away goal changed matters entirely. KR Reykjavik played far more defensively against Celtic than they normally do in the Icelandic championship - their manager admitted as much - and they will have to come out of their shell if they are to have any chance in Edinburgh. Celtic made a handful of second-half chances against them even when they were keeping things tight, however. Deila was fully entitled to his view that there will be more goals for his team at the famous old rugby ground.
By the time of the rematch Celtic will have know which club lies in wait. The draw for the third round will be made tomorrow but Deila knows that as one of the seeded clubs he is looking at opposition such as Maribor, Legia Warsaw, Partizan Belgrade, Debrecen, Slovan Bratislava, HJK Helsinki or Aalborg. Each of those represents a more demanding challenge than KR Reykjavik, of course.
There were moments in Iceland when there did not look to be enough protection for Virgil van Dijk and Efe Ambrose, but the two of them had enough quality to comfortably win their one-on-one battles with the KR forwards. Deila's commitment to swift attacking play will have to be accompanied by a recognition that defenders cannot be left exposed against the stronger sides Celtic will soon face. Still, his first real test was passed satisfactorily. No more, no less. In terms of building his name in Scotland, it was an unfussy start without first night nerves.