But, as Brendan Rodgers calls for others to step up, it may be that someone else will have to arrive in the summer to step in.
When Rangers came flying out of the traps on their first visit to Celtic Park in the opening weeks of the season, it was McGregor who turned the tide.
Carefully and concisely, he took stock of what his team was up against and he set about finding a way around it.
Clever understanding of the situation, one piece of positioning, one break, one pass after 10 minutes of assessment to set Nicolas Kuhn away to set Kyogo Furuhashi up to put the ball in the net.
The strike was ruled out for offside but the whole narrative of the contest was changed.
Celtic went on to win with the skipper scoring the clincher in a commanding 3-0 success. It wasn't the first time McGregor had done it.
But when Rangers replicated that September start on away turf last Sunday and the home captain wasn't around, there was no-one in Rodgers' side to do what their leader can.
That's hardly a brutal criticism. Quite simply, McGregor is a one-off not just in the Celtic squad, but in the country. And it's almost impossible for any individual to do what he does.
Rodgers said as much when stating: "The tactical balance he gives the team. He's the guy that opens up everything for us.
"His movement, his quality his touch gets us through the pitch nice and quickly. So you could see it wasn't anywhere near as fluid.
That's the reality. But, others have to step up because if he's not playing, then we need to be better." Clearly, Celtic have outstanding players in the middle of the park. Each with their own traits and individual styles and talents.
Of course, they all have the ability to do something special at any given moment.
However, at this stage, none of them have shown an ability to boss and control the entirety of a major game in the way that McGregor can. That is the next step for them and it's down to someone to grasp it.
Reo Hatate was the senior figure in the midfield and he had his moments in the match. The Japanese produced a superb strike in the opening period which needed a fingertip save from Jack Butland.
He hit a volley into the sidenet before producing a sublime finish to make it 2-2.
Even when stung by Hamza Igamane's late effort, Hatate still had time to deliver a pinpoint centre that Alistair Johnston should have buried to make it 3-3 at the death.
Hatate does things that take the breath away but he hasn't dominated a major game since signing. It's more special moments.
It was Luke McCowan who produced the sensational pass for Hatate to score against Rangers and he has had less time to stake a claim.
The former Dundee skipper looks the type who could play in that position just ahead of the back four. He has movement and passing range but there are still areas to improve and th...