But now the 19-year-old wants to savour the joy of hitting the net at Celtic Park.
The midfielder's goal to open the scoring in the 1-1 draw with NK Maribor in Slovenia followed his strikes in Reykjavik and Warsaw - but this could be the most important of them all, with £15million on the line.
And if McGregor could break his home duck in the return leg next Tuesday to help the Hoops shoot through to the Group Stage draw, which takes place a week today, his soaring reputation in his debut season will go off the scale.
The Bhoy-wonder remains totally grounded, despite his amazing start to the campaign, and said: "I really don't know why all of my goals this season, in Europe and in the league, have come away from home. Hopefully, I can rectify that next week when Maribor come to Glasgow.
"For now, I am just delighted to get another goal in Europe and keep that scoring vein going and also extend it into games at home."
McGregor replicated his early strike in Warsaw, when he opened the scoring only for the roof to fall in on Celtic as they crashed 4-1. He feared that, when Maribor drew level last night, it was going to be a case of deja vu.
But the fact Celtic not only denied the Slovenians any more goals, but also created a handful of excellent opportunities to grab the win themselves, convinced McGregor this team is learning - fast. He said: "It was disappointing that, like in Warsaw, we couldn't have held on to our lead for a bit longer.
"But, we didn't crumble, and that shows we have come far since the last round. The boys all know what they are doing now, the job the manager wants us to do defensively. Offensively, we are also starting to click a bit."
Despite this improvement, and having that vital away goal, McGregor is already streetwise enough to understand nothing is guaranteed. That's a hard lesson he has learned in this crazy Champions League run.
He said: "We can't take anything for granted. Football is full of twists and turns. We got a decent result last night, but we need to be fully focused on finishing the job."
Celtic go to Inverness on Saturday for a top-of-the-table clash with Caley Thistle, with Ronny Deila considering resting a number of his players
But being back at Paradise for Tuesday's play-off return is already exciting the youngster who can't wait to play his first-ever top-team game there.
He added: "A Champions League night at Celtic Park is something special. When that music plays, and the crowd start cheering, it is like nowhere else.
"It will add to this game and this occasion. Getting to the Group Stage means everything to everyone at the club, so we will definitely be fully focused on that."