MAKING your debut for Celtic is a daunting prospect for a young lad in a domestic fixture.
But taking your first-team bow in a Champions League fixture, when so much is at stake for the Parkhead club, is a massive ask.
Qualifying for the group stages of Europe's premier club competition is of huge importance to fans who have grown used to their heroes playing at that level over the years.
And taking their place alongside the leading clubs on the continent is also vital for the Scottish champions financially; they banked a cool £15million after doing so in 2013.
So, the pressure that was on Callum McGregor's slender shoulders as he took to the field in the KR Vollur Stadium in Iceland before kick-off on Tuesday night was absolutely huge.
The 21-year-old was given the nod to start the first leg of the second-round qualifier against KR Reykjavik in the absence of injured captain Scott Brown.
However, the midfielder justified the faith shown in him by Celtic manager Ronnie Deila, who was taking charge of his first competitive match, and then some.
He performed superbly in the centre of the park and, after Kris Commons, Leigh Griffiths and substitute Teemu Pukki had all hit the woodwork, netted the winner with just seven minutes remaining.
The Scotland Under-21 internationalist's display has put the Glasgow club in a commanding position ahead of the second leg at Murrayfield next Tuesday.
The massive impact that McGregor made in the Champions League tie took many Celtic fans aback - but it came as no surprise to anybody who has worked with him in the past.
He spent last season on loan at League One club Notts County, and their manager Shaun Derry fully expected him to cope with the occasion despite all the expectation that was upon him.
For McGregor played a massive role in helping the Magpies avoid the drop from the third tier of English football and even finished the 2013/14 campaign as top scorer with 14 goals.
He banged in important goals in wins against Crewe, Oldham, Bradford City, Gillingham, Colchester and Swindon to help County finish just three points above the drop zone.
Derry recalled: "A huge amount of responsibility was placed on Callum at a very young age at Notts County last season and he handled it very well.
"Callum had a fantastic season for us and I am sure it was an invaluable education for him to be involved in our successful attempt to stay up so early in his career.
"He was brilliant for us on the park and, more than that, he was a great lad to have in the dressing room and around the club as well. We were glad that we had him.
"We were keen to keep him, but he wanted to go back to Celtic and fight for a place in the first team. I am pleased to see he has made the breakthrough and am sure he will go from strength to strength."
As a result of his bright performances for Notts County during the first half of last season, several English clubs started to show an interest in signing McGregor.
It was reported back in January that Celtic were prepared to do a straight swap with Wolves for him - with Scotland international striker Leigh Griffiths going in the opposite direction.
That move, though, was flatly rejected by the Molineux club and Griffiths ended up being sold for £1mon the final day of the transfer window.
Having scored no fewer than 12 goals from midfield for a lower-table club in the opening months of the season, the young Scot soon had an £850,000 price tag put on him.
But Notts County successfully negotiated an extension to his stay at Meadow Lane after that - a moment that Berry felt was pivotal in their battle to stay up.
He said: "We felt that if we had lost Callum in January then it would have made our task of staying up far, far harder. It was a huge boost for myself and for the Notts County fans when we managed to hold on to him.
"Callum was desperate to stay with us for the second half of the season and we were desperate to hold on to him. We were all grateful to Celtic for being so good to deal with at that time.
"He stayed and trained with us after his initial loan deal expired. That was a testament to the character of the lad. There was interest in him from League One and Championship clubs. But he was keen to stay with us and continue his development.
"It was still far from plain sailing after he stayed. But having a player of his undoubted quality on the park was certainly helpful to us. In fact, I think it was a turning point in securing our safety. We loved having him at Notts County.
"I was unbelievably impressed with how well that he did when he was at the club at such a young age and I know the fans were as well. He is a special talent and has a bright future in the game."