The Norwegian prospect has been a sensation for Celtic throughout 2019.
It's easy to forget sometimes that Celtic defender Kristoffer Ajer is still just 21-years-old.
With close to 170 senior appearances to his name already, along with ten caps for his country, the experience he has gained is excellent considering that's a novice age for many young players.
It's not just his profile that betrays his age though, but the way he conducts himself on the pitch also.
Over the last 12 months he's emerged as a real leader within the Celtic defensive unit and someone who the Hoops should be looking to build a team around.
As we know though there are realities to consider when outstanding talents make a name for themselves at Celtic Park.
Given the nature of the modern game, the likelihood is that one day a cash rich club will come calling for the young Norwegian.
That shouldn't be seen as a negative prediction however, but one which demonstrates the success Celtic have had in developing young talents at the club.
Signed as a budget project by Ronny Deila on a pre-contract basis in 2016, could Ajer be Celtic's next £20m+ departure and become the latest example of a successful development model?
The sale of Kieran Tierney to Arsenal has set the bar at Celtic in terms of outgoing transfers. The fee for star players leaving Glasgow has been creeping ever higher in recent years.
From the departures of Victor Wanyama and Virgil van Dijk to the massive exit of Moussa Dembele, the club have been holding out for increasingly bigger amounts.
The £25m for Tierney is a new watermark though. Any team looking to come in for Ajer, or others such as Odsonne Edouard, better be prepared to pay the guts of that fee.
This summer's business has no doubt increased Ajer's value by default.
There's no doubt that Brendan Rodgers has had a big say in Ajer's development. The player was on his way to becoming a big player for the Hoops throughout the former manager's spell in Glasgow.
However, the faith shown by Neil Lennon in the defender is one of the biggest indicators of the potential he holds.
Incredibly, Ajer has played in all but two of the matches that Lennon has taken charge of since arriving for his second spell at the club in February.
One was due to injury, with the player missing last Sunday's trip to Ibrox, and the other was a simple case of being rested against Nomme Kalju after a dominant first leg victory over the Estonians.
The Hoops boss already sees as a fundamental part of his side and his influence is only growing. That puts Ajer in the top-tier of almost untouchable talents when it comes to a departure.
Celtic move to strengthen their position
According to a report in The Daily Record last month, Celtic are preparing to tie Ajer down to a new contract.
His current deal expires in 2022 so while it's hardly urgent, signing up the player to a new lucrative contract would demonstrate the strides he has taken recently.
However, it's also a sign that the Hoops are looking to protect one of their key assets.
Their strength in negotiation when it came to Tierney was due to excellent contract management. Celtic knew that they had the player committed to the club well into the next decade and so did not need to be dictated to.
If Ajer similarly commits over the next few months, it's another real indication that the Norwegian is one of the most highly valued stars at the club.
One day that's likely to pay off big for all involved and make the Norwegian one of the most expensive exits ever at the club.
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