Ronny Deila has spoken of his anguish at his failure to see improvements within his team this season.

The Norwegian insisted that it has “killed” him to see the squad stagnate, and he acknowledged full responsibility for the manner in which Celtic have repeatedly crumbled in big games this term.

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Deila will oversee the remaining five league games of the campaign as he seeks to leave Celtic with a fifth successive title and the second Championship of his reign, and he is optimistic that this week’s announcement about his imminent departure lifts the pressure off the club.

“It has been a tough six months,” said Deila. “You have asked me many times about improvements and I haven’t answered those questions really well over the last month.

“That’s why, in the end, it kills me that I don’t think the team has improved in the last six months.

Glasgow Times:

“That’s my responsibility. One of the reasons we haven’t improved so much is that we have lost important games and the pressure on me has been more and more. That also affects the players and the whole surroundings.

“That’s why I was thinking this is the best thing for me and the club, to come out now and give everyone an answer.

“I feel I haven’t got the results and improvement I wanted.

“Now we can focus on the last five games. That’s the most important thing for the club and for me, to get the results and win the league.”

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And Deila has maintained that his decision was unaffected by Sunday’s defeat in the Scottish Cup semi-final to Rangers.

It was a humiliating defeat for the Parkhead side but Deila had already made his mind up that he would be gone at the end of the season. Whether or not he would have been allowed to remain in the post had he not opted to quit is another matter, but certainly the dignified exit suits both parties.

“Even if we had beaten Rangers, I wasn’t happy with the performance,” he reflected.

“It wasn’t only that performance. It has been overall for a while now. There hasn’t been that energy I need from my teams. So that has nothing to do with the Rangers game.

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“Of course, it was a hard blow but it was not the final thing.

“It is about development. That is one of my biggest things. I don’t do things to win. Of course, I want to win - but I have to win while seeing things are progressing and by playing attractive football.

“Those two things haven’t been as I wanted and that’s why I have come to this decision, because it kills my energy.

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“When the team is not taking steps, you have to look at yourself in the mirror and ask ‘What is happening here?’.

“I have tried for a long time but you can’t keep on going. You have to think about the club as well.”

Deila remains adamant that it is possible for the club to reach the group stages of the UEFA Champions League – but he believes there would have been too much pressure around the players had he been given a third crack at getting the club into the tournament.

“I have tried for some months now,” he said. “Hopefully the club will be going into a Champions League qualifying campaign again this summer and with the two defeats in the two previous years, there would be even more pressure on me and everyone else.

“It is good for the club now to get new energy in for the start of next season. Because I really care for the club, I’m very fond of it and I will always be a supporter.

“But I just haven’t got that improvement that I wanted. That’s hard to say. It’s something I have to reflect on after the season. Of course, there are things I could do better and things I have done very well. It’s not black and white.

“But in the end, the total results haven’t been good enough.”

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