It is sometimes easy to forget that Celtic splashed out the best part of eight million quid on just two central defenders last summer. Neither Gustaf Lagerbielke nor Maik Nawrocki have managed to make an impression on Brendan Rodgers’ starting XI on anything approaching a regular basis.

In fact, neither have managed to climb above Liam Scales or Stephen Welsh in the pecking order of the central defenders at the club, never mind live up to their price tags, which is as damning an indictment on their respective abilities as it is to the recruitment process that brought them to the club at such cost.

Perhaps one or both will come good at the club in due time, but that is a commodity that is in short supply for Celtic. They need tried and trusted performers in the here and now as they enter the critical final stretch of the season, with the thin thread by which their hopes of success hang laid bare in the absence of Cameron Carter-Vickers against Livingston at the weekend.

The partnership of Scales and Welsh that were on display was full of honest endeavour, but the chasm in the quality they possess to Carter-Vickers is stark. Defensively, Livingston were able to trouble them of course, scoring twice at Celtic Park and fashioning a couple of other presentable opportunities that could have made a dicey situation at the club a disastrous one had they been converted.

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More than that though, the absence of Carter-Vickers has a huge knock-on effect in the entire set-up of the team. Something that Rodgers himself has alluded to.

Carter-Vickers is often the catalyst for Celtic’s attacks with his forward passing. Without him, there were far too many balls played across the backline at the weekend, and even then, many of them were played behind their target, slowing down the attacking phase before it had even got going.

The fact they were also missing captain Callum McGregor was an added issue in getting the ball through the pitch, but the fact that the defensive line was having to sit deeper too to compensate for the absence of the pace of Carter-Vickers also caused a problem going the other way, opening up spaces in the field that otherwise would not have been available for Livi to play in.

So, without the American international, Celtic are not only susceptible to attacks from the opposition, but are diminished too when they are in possession. They become disjointed, less sure of themselves, and a lesser team.

That is to Carter-Vickers’ great credit that he has become so indispensable, but it is to Celtic’s detriment that they are so reliant on one player, particularly as his entire campaign has been plagued by a spate of injuries caused by underlying issues associated with his knee operation in the summer.

In short, it is little wonder that in a season when Carter-Vickers has been available for selection on such an inconsistent basis, that Celtic have been so inconsistent.

It was with some palpable relief then that Rodgers was able to relay some positive news to supporters yesterday regarding the fitness of his star defender, with the Celtic manager confirming that his precautionary absence from the side for the Scottish Cup win looks to have eased his hamstring issue.

"We will have a look at Cameron Carter Vickers [for Saturday’s game against St Johnstone], he should be fine, it was precaution," Rodgers said. "I spoke to Cam at length this morning, he just feels everything is based from around his knee operation.

"Also, when you have picked up a few injuries from that, you get that sensation and think it's linked to another injury. Thankfully, it doesn't seem to be that.

"We've had the scan which has come through fine, he's done some work with the medical team and hopefully he will rejoin the training squad on Thursday and Friday.”

Celtic have nine league games left to play as well as two – they hope – in the Scottish Cup. If they are to emerge from this season with a domestic double despite their frequent troubles, they will undoubtedly need Carter-Vickers to be present for the vast majority of them.

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The trouble is, his longest run of games this term was the five consecutive matches he managed between November and early December. He has missed 12 of Celtic’s 29 league games, and has yet to play in the Scottish Cup.

His chances of suddenly finding the physical robustness required to lead his team to glory seem slim, then. But their chances of glory, seem to hinge upon it.