BY his own incredibly high standards, the past couple of weeks haven’t been good ones for Kristoffer Ajer.

The Celtic centre half conceded a penalty in the Europa League group game against Rennes in France a fortnight ago with a needless challenge to scupper his side’s hopes of recording an invaluable away win.

He then scored an own goal at Easter Road at the weekend as the Parkhead club drew 1-1 with Hibernian and dropped their first points in the Ladbrokes Premiership this season.

Yet, the Norwegian internationalist hasn’t simply tried to forget about those mistakes and move on since. Anything but.

He has been poring over video footage of those incidents in an attempt to avoid making the same costly errors in future. He is confident he will be able to get back to his very best against Cluj in the Group E match against the Romanians at Celtic Park tonight and can contribute significantly to a victory.

“I’m a young guy who wants to learn as much as he can,” he said. “To go through every game with John Kennedy (Celtic assistant manager), who was also a centre-half, to learn tactically is very important and helpful for me.

“There’s always something you can pick up. As a human being, you will make mistakes but the important thing is that you learn from them and, hopefully, you won’t repeat them.”

“I have looked through the penalty in Rennes several times and learned from that. That will hopefully not happen again. I have looked through the own goal against Hibs a few times as well.

“The penalty against Rennes? I absolutely could have and should have done better. It’s a learning experience. I look through all the clips with Kendo and we try to learn from it. The most important thing is it doesn’t happen regularly and hopefully it won’t.”

“It’s the most important thing as a footballer. It is easy to look through good games when everything is going smooth and you perform well. But they aren’t really the important games to look through. Those nights when you have been out of position, when you have been struggling a bit and you come off and think after the game ‘I was involved in too many situations tonight’.

“Then it’s important to look through and learn from them. The backroom staff here work incredibly hard. I have never been at Lennoxtown when they haven’t all been in. I think it sums up this club. Everyone works so hard.

“I love playing for this club, but I know there are huge expectations playing for this club. You are only as good as the last game you played. You have to improve and keep having good games. But I enjoy the pressure, enjoy having to play well. You always have to perform.”

The 4-3 defeat to Cluj in Glasgow back in August – a result which saw Celtic crash out of the Champions League in the third qualifying round for the second season running – is another match he has watched back repeatedly with his team mates in the hope of eradicating their slack play at the back.

“We’ve looked through what we did wrong against Cluj and the backroom staff have worked really hard by showing us footage and pointing out how we can improve,” he said. “We’re looking forward to this game.

“Obviously, they got the better of us at Celtic Park and it was an annoying night for us. We have to do better this time and get the points we need. You always want to concede the least amount of goals possible so to lose four against them – especially at home – wasn’t good enough. We’ve looked through all part of that night and learned from it.

“We had everything planned well for the night and everyone was ready, but we were just a little bit flat in the first-half. We just conceded a few bad goals. That’s hopefully something we can avoid tomorrow.”

Celtic manager Neil Lennon left his new signing Boli Bolingoli, who had performed poorly in the first leg against Cluj away, out of his side that evening and played Callum McGregor out of position at left back. His side failed to function normally at the back and paid a heavy price for that.

Ajer believes Bolingoli has improved and grown in confidence since and will help Celtic to produce a far superior showing against Dan Petrescu’s side in their rematch.

“Boli’s been really good since he came in and he’s settling in very well to life in Scotland,” he said. “It’s only natural that, the moré games you play, the new defenders will learn from each other and talk to each other more. We’re doing that every day in training and we watch clips from every one of our games.”

Bolingoli wasn’t the only new arrival who was finding his feet in the East End when Cluj last visited. Ajer, who has struck up an impressive central defensive partnership with Christopher Jullien in recent weeks, believes the new-look squad has gelled successfully on and off the park since then.

Asked about his relationship with Jullien, he said: “I still don’t speak fluent French but I’m trying my best because his Norwegian isn’t good enough! Seriously, this is the best dressing room I’ve ever been part of.

“Since I came to this club everyone has been so united and the new guys who have arrived this summer have been no different. Everyone has been made to feel that they are included and that makes for a healthy environment.

“You need to have different characters to create a good atmosphere. You also need leaders like our captain. He’s been fantastic and there are so many other Scottish players – and a few foreigners! - who know what it means to play for this massive club.

“Now we have three Norwegians so we’re starting to form our own wee group! Seriously, I don’t feel that way at all – everyone is speaking to and laughing with each other. It’s a really good group.”