What a difference just a few weeks makes in football.

Celtic’s squad depth is not in a good way. Carl Starfelt found himself trading Scotland for Spain, joining La Lega regulars Celta Vigo after two years at Parkhead. This exit was not unsurprising, as there had been talk throughout the season that Starfelt may look to ply his trade elsewhere, with the added complications of off-field relations also playing a part in his wish to move on.

This departure was swiftly dealt with, following the signing of Gustaf Lagerbielke, who joined the club from Swedish side Elfsborg. It was assumed that the 23-year-old would be fighting for one of the two spots occupied by fellow summer signing Maik Nawrocki and Cameron Carter-Vickers. This move – coupled with the contract extension of Stephen Welsh – had many feeling optimistic about the defensive side of things, with the likes of Liam Scales and Yuki Kobayashi potentially looking elsewhere for first-team football.

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However, the past two weeks have been devastating for Celtic’s defensive aspirations, thanks to a sudden raft of injuries to the backline. The first was Carter-Vickers, who came off as a precaution due to a hamstring twinge after the first half against Aberdeen at Pittodrie. Just back from a separate injury to his knee, the American international is now again an injury doubt. In a positive sense, that blow gave Welsh a chance to shine alongside Nawrocki, and the pair did well after the interval, stabilising themselves at the back to guide Celtic to a 3-1 victory away from home.

Brendan Rodgers was clearly a fan of Carter-Vickers’ replacement. In the days that followed the game, the club announced that Welsh had signed a new four-year deal with Celtic. A solid enough deputy that fulfils the homegrown quota needed for the Champions League squad, the general consensus was that this was effective management by both the manager and the club in tying the player down on improved terms.

Bad luck is one thing, but having no luck whatsoever is another, and this was perfectly exemplified by what happened following the signing of this deal. The ink would barely have been dry from the pen used to finalise the contract when it was announced that Welsh had suffered a knock in training on the same day. This was followed by a picture of the defender wearing a protective boot in a hospital waiting room on social media, pointing to a more serious issue.

In what was truly a weekend to forget for Celtic – where the club went out of the League Cup at the earliest possible opportunity against Kilmarnock – it was announced prior to the match that Welsh had ruptured ligaments in his ankle, in turn ruling him out for at least two months. These developments essentially forced Rodgers to deputise Lagerbielke alongside Nawrocki in the centre of defence in what was a baptism of fire for the new defensive partnership.

Celtic’s luck would run out in more ways than in Ayrshire. Compounding the loss was yet another injury to a central defender, this time in the form of Nawrocki. Having completed just three professional games for his new club, the Polish defender is now set for a spell on the sidelines due to his hamstring injury. For a side that was stacked to the brim with central defensive talent both on the pitch and waiting in the wings, the situation has drastically changed. Question marks were already swirling regarding the state of the defence as a whole - with the centre being the strongest position – but that does not look to be the case at present.

At present, it could be argued that the strongest defence that Celtic can field is that of Anthony Ralston, Lagerbielke, Scales and Greg Taylor. This is a sobering thought, especially when you factor in the magnitude of fixtures that Celtic have coming up in the near future. Yes, they will first face an admittedly poor St Johnstone side at Celtic Park – which that defence should surely be able to deal with sufficiently, you would hope – but Rangers await them the week after in the first Glasgow Derby of the season.

No matter how the opposition shapes up or what their form is like going into the game, the thought of that backline lining up at Ibrox on September 3 is a frightening prospect. The only grain of positivity stemming is the potential return of Alistair Johnston for that game, which would be a massive boost. His experience in a back three may even prompt Rodgers to potentially deploy him as a central defender if needed, although this would not be ideal. We have already seen the pitfalls of rushing a player back too quickly in Carter-Vickers, so the club may elect to be more cautious with their other North American asset.

At least on an individual level, these injuries have opened the door for those perhaps on the periphery of things to come in from the cold and stake a claim in the team. Although their futures may lie elsewhere in the long term, both Kobayashi and Scales could play a role in the weeks and months ahead. If they cannot step in and do a job, then a short-term solution may be sought by the club in order to plug these gaps, such as a loan or a free transfer signing not already with a new club.

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Remember when Rodgers returned to the club over two months ago? He spoke about his hunger to continue Celtic’s dominance of the Scottish game while also making a dent in Europe. He cannot realistically do the latter with the current defenders fit and available to him. In his first press conference since returning to the club, he said: "I think the draw of getting into the Champions League and what it does for the club financially is great but I’m here to win and I want to win.  It’s why I’ve come back, is to win and see what we can do in Europe.  Europe’s a huge part of the history of this club.

"I also understand the challenges having worked in the Premier League and the budgets of those clubs which far supersede what we can pay, but we want to be competitive and that’s what’s important for us. Some will define success differently, but certainly, a win in the knockout stages would be a good start.”

One would hope that these aspirations have not been altered or discarded just a few games into the season. As much as injuries cannot be helped, the current situation is far from ideal. Time is truly of the essence in order to remedy this.