With Jozo Simunovic sustaining an injury on international duty with Bosnia & Herzgovina recently, it brought into sharp focus Celtic's woes with injuries in defence in recent months.

The big defender may be back in training, but unavailable for selection against Dundee, it again gives Brendan Rodgers something to think about when it comes to selecting his defensive line.

When injuries have occurred there this season, Rodgers has opted experiment with a back three, however, it's when the Hoops have a solid back four and their familiar midfield shape that they truly shine.

Short on defenders, the Celtic boss has called upon the likes of midfielder Nir Bitton and the inexperienced Kristoffer Ajer as solutions, although neither have solidified their place in his starting line-up.

The Ajer option is an intriguing one though and one that should be explored further, instead of tinkering with players out of position.

Here are three reasons why...

Injury problems continue

With the amount of games Celtic play a season, which can be close to sixty if they perform well on all fronts, three centre-backs simply isn't enough across an entire campaign whether utilising a back three or a back four.

Dedryck Boyata's injury history is notable, missing a large percentage of matches over the past 18 months due to injury. With Erik Sviatchenko also sidelined for much of 2017 and Jozo Simunovic having his own muscle problems, to the extent he doesn't usually feature on artificial pitches, it means Brendan Rodgers needs a capable option ready to step in.

With just five appearances to his name in Celtic colours, Ajer hasn't had enough experience to be regarded as reliable in big matches and needs more exposure to first team football, such as the one this weekend against Dundee, an opponent who won't pose as stern a test as others home and abroad.

A better option that Nir Bitton

Nir Bitton is an experienced player with a cool composure that is well suited to Celtic's possession-based game, but the midfielder is not a natural defender and in his few appearances at centre-back so far has at times looked less than accomplished, being caught ball watching or out of position when balls come over the top.

Kristoffer Ajer may not be the finished product himself but at 19 year of age is a far better long-term prospect in the position. Remember, it was Brendan Rodgers himself who dictated he should pursue a career at centre-back after the Norwegian arrived at the club as a midfielder.

With games alongside established defenders like Jozo Simunovic, his skill as a defender could improve rapidly and when others are unavailable, the Celtic boss shouldn't be turning to the likes of Nir Bitton instead, which he has done already this season.

Attitude and determination to succeed

Kristoffer Ajer's warrior spirit was on full display during the international break when he dislocated his shoulder during a match with the Norwegian U21s side. It was a crucial qualifier against Germany and the player insisted he would not be substituted off, instead having his shoulder popped back into place to continue the match.

As quoted by The Herald, the teenager said of the incident: "When you play for Norway, there’s a hell in you. The shoulder jumped out a bit, but I got it in place, and then it’s okay. You just pull it into place and get on to the pitch When you play for Norway, you do not get lost because your shoulder is jumping out. I refuse to do that. It means a lot to play for Norway."

That's the kind of attitude that could make him a massive hero with the Celtic support. Who doesn't want a defender that is willing to sustain injury and play on for the cause of the team?