CELTIC boss Ronny Deila today vowed to persevere with his bold plan to bring European success back to Parkhead.

But he revealed he'll "go back to Norway" if his methods are rejected in Scotland.

The former Stromsgodset manager has introduced new tactics and a strict diet and fitness regime since arriving in Glasgow this summer. He is adamant that the changes are needed to compete with Europe's top clubs.

He said: "I have to believe in my way. When you come to a new club it takes time.

"You can ask the new Manchester United manager Louis van Gaal about that. He has hard discipline and knows what he wants.

"We are taking some chances with our passing. But if you don't make mistakes, you don't improve. If you always play the same way, you will get the same things.

"If you don't want to develop, you will never get anywhere. You will always be the same - boring for a long time.

"I want to do something with a big club and you don't do that in days or weeks. You do it in months or years.

"But are we talking Scotland or are we talking Europe?

"To win in Scotland, we can still do the same things as before. But to succeed in Europe, you have to adapt to Europe."

Deila added: "If you see the fitness in the Champions League it's unbelievable.

"If we want to do that then we have to look outside the country, not inside.

"hat's because the levels are not inside the country, they are outside.

"If you tell me that a player can be three or four kilos too heavy and play against Ronaldo, then good luck.

"You have to understand that the fitness is unbelievable out there.

"If you see Gareth Bale, that's Champions League level.

"So are we not going to try to adapt to that? Do you think Andy Murray eats chips?

"If Celtic or Scotland are not ready for that, then I will go back to Norway. It's no problem.

"I'm here to do something, I want to make something here.

"If you don't do it, then okay, I tried.

"But I really believe the players are enjoying it and they want to adapt to it. I am so satisfied with their attitude."

Deila's predecessor Neil Lennon, who steered Celtic to the last 16 of the Champions League two years ago, has dismissed suggestions that his players weren't fit enough.

But the Norwegian, whose side take on Dinamo Zagreb in the Europa League at Celtic Park tonight, insisted he had the full backing of major shareholder Dermot Desmond and chief executive Peter Lawwell.

He said: "Dermot and Peter are very intelligent. They have seen football for many, many years. They know how to build things.

"They wanted a change and that's why I came in.

"If not, they would have gone for a manager with much more experience and would have done it more like it was done before.

"Maybe I see things differently from what Neil was doing.

"For me, to be professional is to be a 24-hour athlete.

"If not then you can go and start working outside football. That's not so hard. You can be amateurs again.

"You have to understand that I can't be stupid when I say things like that.

"If Neil gets irritated by me saying we can work on how we eat and improve that's up to him.

"For me, I think from what I have seen abroad and what I have experienced myself it's important. We have different ways to do it."