IT is sometimes easy to forget just how young Kristoffer Ajer is. The Celtic defender is just 20 years old, yet regularly displays a maturity that makes a mockery of his age. It’s always been this way for the Norwegian, who made his professional debut in his homeland for Start at the age of 15 and became the youngest-ever captain in the history of the Norwegian top flight less than a year later.

After racking up 54 appearances for Start at just 17 years old, Celtic brought Ajer to Scotland and the defender has developed into one of the finest young centre backs in the country. The Norwegian’s form was recognised by his national team last March, and Ajer has gone on to make six appearances for the senior Norway side since.

As Ajer continues to go from strength to strength at Celtic Park, the towering centre half’s influence is growing in the heart of the Celtic defence. This is in part down to the somewhat unique skill-set Ajer possesses; dominant in the air with an eye for a pass and comfortable with the ball at his feet, there isn’t really another defender in Scotland quite like the Norwegian at present.

There used to be another player who turned out for Celtic who had a similar style of play, though. Virgil Van Dijk is now widely accepted to be one of the best defenders in world football, and there are certainly shades of the Dutch international in Ajer’s style of play.

READ MORE: Rangers are making steady progress under Steven Gerrard

Van Dijk has made a name for himself as one of the great headers of the ball in European football and this is a trait that is apparent in Ajer too, albeit to not quite the same standard. The sheer size of the Norwegian certainly helps here - Ajer measures in at about 6 foot 5 - but the Celtic defender is second to none when it comes to aerial prowess in Scotland.

Ajer wins 75% of his headers for Celtic, the highest success rate of any Premiership player. This ability to calmly deal with lobbed balls forward brings a sense of calm to the Celtic backline; an invaluable asset at any level of the game.

READ MORE: David Preece broadens his horizons in search for new ideas

Ajer’s eye for a pass is another of the young defender’s traits that make comparisons with Van Dijk almost inevitable. The 20-year-old has the sixth-highest passing rate of any Premiership player, and the fifth-highest passing accuracy with a mightily impressive 93.56% of his passes finding their intended target.

Critics will be quick to point out that Ajer benefits from playing for a Celtic team that dominate possession in virtually every domestic game they contest, and that Ajer is playing simple passes that are difficult to get wrong. There is some truth to this: when the Norwegian spent a season on loan at Rugby Park, for instance, his passing accuracy fell to a not-so-impressive 78.1%.

READ MORE: Kieran Tierney: I wouldn't be here if it wasn't for Mr Celtic John Kennedy

But the second point - that Ajer is playing easy passes - simply isn’t true. Ajer has the second-highest accuracy rate in terms of passes into the final third of any Premiership player. Only his team-mate Filip Benkovic - who is valued in the tens of millions - is more accurate, and even then the difference is a marginal 0.5%.

This composure on the ball is certainly reminiscent of Van Dijk. One of the Netherlands internationalist’s greatest strengths is his ability to distribute the ball from the back, and start attacks from deep. Now, Ajer isn’t quite at that level yet but the Norwegian is showing that he is capable of playing in such a manner.

READ MORE: Oliver Burke ready to lead line for Scotland

One of the traits that makes Van Dijk truly stand out on the pitch is the centre back’s ability to carry the ball and break forward into midfield, and this is an ability that Ajer shares. Progressive runs are dribbles completed by a player where they carry the ball at least ten yards up the pitch and again, Ajer is one of the Premiership’s best players in this regard.

The Norwegian averages 3.9 progressive runs per 90 minutes; only Kilmarnock’s Jordan Jones has a higher rate of these kinds if dribbles. This ability to break out of defence isn’t exactly a necessary requirement of a modern central defender, but it is certainly another string to Ajer’s bow that makes him a more dangerous opponent than a traditional centre back.

It will be very interesting to see how Ajer is deployed under Neil Lennon going forward. After all, Lennon is one of the coaches who helped develop Van Dijk into the player he is today, but the Northern Irishman is seemingly reluctant to set up his team to play out from the back. Ajer's development could hinge on this; if he is asked to play a simpler role in the Celtic backline, then the rare assets that he possesses as a defender could be damaged.

All in all, it appears as though Ajer is on the right track to becoming an excellent defender and his career is certainly one worth watching closely. No-one is saying that he will hit the heights that Van Dijk has, but the similarities between the two players' style of play are startling. Clearly, it is unlikely that Ajer will be able to match the Liverpool defender’s career, but there are plenty of indicators to suggest that the Norwegian is a player in a similar mould to the Dutchman. If Ajer continues to develop as he has done so far at Celtic Park, there is every likelihood that he could be the latest Celtic player to move on to bigger and better things in the future.