Celtic defender Kristoffer Ajer has spent much of time bulking up in Glasgow in order to muscle his way into the Hoops backline. And the teenager has insisted that he puts his body on the line for Celtic every time he pulls on the shirt.

The Norwegian under-21 internationalist came to the fore last month as he helped Celtic to four consecutive clean sheets following the Tynecastle defeat that brought an end to the club’s unbeaten run.

Ajer will be expected to retain his place for tomorrow afternoon’s visit of Brechin in the William Hill Scottish Cup but with Rodgers insisting that he does not need to beef up his defence in this window, Celtic may seem a little more of the teenager. Certainly, with Marvin Compper’s debut delayed because of a calf injury and Erik Sviatchenko having returned to his homeland, Ajer will expect to hang onto the starting jersey.

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“I’ve developed a lot in the last six months under the gaffer,” said Ajer. “He has helped me a lot and put faith in me. It’s been really good.

“I feel more secure as a centre half now. When I came here I was a midfielder but I feel more secure as a centre half now. I needed time to get into the new role and understand how the gaffer wants central defenders to play.

“The loan out to Kilmarnock also helped because I played there every single week as a centre half. I’ve been in the gym after every training session since day one here. It’s been beneficial for me to bulk up a bit. I’ve got a really good programme to follow in terms of bulking up and explosiveness and also technical stuff on the pitch.

“We have really good central defenders here and we’re training hard every single day and really pushing ourselves. For me as a young guy I’ve learned so much from all the central defenders, including the latest Marvin Compper. It’s something different to play for Celtic. When you go out and hear 60,000 fans screaming and hoping you win then you put everything you can into the game - I’m sacrificing my body for this team.”

Such has been the nature of Ajer’s performances that he is expected to be called up for the senior Norway side in March for friendly games.

And while that might underline the impression that the defender has made on the side, his focus at the minute is on sustaining the form he has established at Celtic.

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“It’s the end of the March the next international and that’s a long time,” said Ajer. “It would be a bonus for me because at the moment I’m only 100 per cent focused on playing for Celtic.

“To just be here at Celtic and do my best is the biggest thing for me.

“To be fair, I haven’t really spoken to anyone back in Norway. I put that aside anyway and just focus on my development with Celtic.

“When you play for Celtic every game is big. Now it’s Brechin and we’re looking forward to it. As a Celtic player you put yourself into a good position to play good games. I focus on myself and if I do well then hopefully the big games will come.”

Ajer’s formative years were spent looking up to former Norwegian captain Brede Hangeland, whose career also started in midfield before taking a step back.

“It was Hengeland who was the captain of Norway for a long, long time,” said Ajer. “He was someone I admired and he played also as a central midfielder in Norway when he was younger.

“We’ve taken a similar path. But obviously he played a lot of games in Norway and I’ve still got a lot of development to go to reach his level. When I was 15 and involved in my first national squad he was there to talk to us and give us information and advice.

“He was the captain of Norway and a big, big player and all of us looked up to him. It was great to see him and get advice.”