Ronny Deila on Pedro Caixinha, his Old Firm heartbreak and rating his time at Celtic

While the two men have never met, on at least one occasion they nearly did.

This was back when the Norwegian was Celtic manager and the Portuguese was winning admirers with the Parkhead side's affiliated club Santos Laguna. Chief executive Peter Lawwell had suggested a fact-finding trip for the two of them out to Mexico to intensify the relationship between the two clubs and help forge a partnership between these two highly-rated young coaches.

"I didn't speak to him [Caixinha] when he was in Mexico but myself and Peter were thinking of going over to visit him," Deila told SportTimes this week, as he prepared for the start of the Norwegian league season with his new club Valerenga.

"I remember Peter talking to me about him. He said the club was good and there was good trust between the two clubs. We were talking about a couple of players."

There is probably a law somewhere prohibiting Celtic managers - past, present or future - offering any assistance to their counterparts across the city, but by rights there should be a solidarity between Deila and Caixinha.

These two foreign imports, and virtual unknowns, were originally mooted for an assistant manager's role, only to impress so much at the interview stage that they soon found themselves parachuted into the Glasgow pressure cooker.

Nothing they had done beforehand could come close to preparing them for what was about to hit them.

Being young, idealistic and strong willed is all very good. But as Ian Cathro is finding out at Hearts right now, you can have all the principles in the world and not get anywhere unless you can also carry a dressing room and buy enough time to implement them.Deila feels partly vindicated by the success he achieved in instilling in the club's players a 24/7 approach to being a footballer, with greater emphasis on diet, lifestyle and factors like injury prevention, but he also accepts that a lengthy CV as a manager, or an illustrious past as a player for the club, usually helps.

"You don't get anything for free in this situation, that is for sure," he said. "But at the same time it is about what kind of motivation you can give to the players.

"There are two things you get respect for in my opinion. One, is how you treat people. And two, is what you know about the game. So if those two things are good you will get the players with you and you can create results."

When that excursion to Central America was proposed, all possibilities still remained open for the Norwegian. Little did anyone suspect back then that two years down the line that Caixinha would be the manager of Rangers and Deila would be back licking his wounds in his homeland.

But the momentum established during a promising first season started to dissipate with a Champions League qualifying defeat to Malmo. A dismal Europa League campaign didn't help, and the straw which broke the camel's back was the semi-final defeat to Rangers in the Scottish Cup last April.

As the two teams prepare to do battle again on Sunday, April 23 - almost a year to the day, yet with Brendan Rodgers and Caixinha at the controls - it almost seems perverse to mention that a break of the ball here and there and Celtic might have won that match.

"Patrick Roberts, almost comically, stuck the ball wide with the goal gaping in the first half, while the luck of the bounce went against them in the dying seconds of extra time when, with the score tied at 2-2, Leigh Griffiths' free kick cannoned off the bar and Wes Foderingham before dropping wide. Penalties, as everyone knows, are a lottery.

But somehow, for Ronny Deila, that wasn't, and isn't, the point. So appalled was both he, and the board, by a performance which he felt was entirely missing his signature that a decision was taken that very night to bring an end things.

It wasn't just Deila's career which was never the same after that day. Old Firm managers, rightly or wrongly, tend to be defined by their team's performances, and results, in this match-up and as impressive as Rangers' performance was, it set a standard which they have struggled to live up to ever since, leaving Mark Warburton as a hostage to fortune.

Whether, as was reported, certain Celtic directors took umbrage at some of the triumphalism in the other end at Hampden that day Celtic have certainly redoubled their efforts ever since.

"I thought Mark Warburton was a gentleman," said Deila, "Although I maybe only met him once or twice. I had enough on my plate with Celtic, I didn't care about the others.

"But this wasn't a Ronny Deila team that went out that day and I was responsible for that. That is why we decided that enough is enough.

"We played so bad, there was no energy in the team, nothing," he added. "That night I understood that if this club was going to go forward and if this team was going to get the best out of itself then I had to do something. I wasn't having fun, because I wasn't improving anything any more. We were standing still, or maybe moving backwards. That was when I talked with Peter and we agreed that this was over.

"We could have won the game but for me that wouldn't have helped everything. We would never have gone in like that, just one year before. We used to play with so much intensity. And that is also what I like when I see this current Celtic team, I see energy, happy people and players. I see a group that stays together and that is the kind of football I love."

Deila is honest enough to admit that Celtic have moved on since he moved on and Brendan Rodgers moved in. He has a new daughter, Isabella, born to his partner Ana in Marbella in September.

He has a new challenge to get his teeth into, at Valerenga, historically the biggest club in Oslo but one which hasn't been good enough to win the top league in Norway for more than a decade.

Sitting in the Vallhall Arena in Norway, he even finally got that full size indoor training pitch he was after.

So, now he is at the safe distance of being back in Norway, how does Deila view his two months riding shotgun at Celtic? And would he ever want to go back to that kind of pressurised existence?

"If you saw it as if I was the best, most experienced manager in the world ... say I was Brendan Rodgers, and had achieved what I had achieved, I would give myself a four [out of ten]," said Deila. "But if you come from Norway, and have no experience, I would give myself a seven."

He speaks about the importance of learning from mistakes and his education in the game hasn't stopped. As recently as December, during down time before the beginning of the Norwegian season, he spent time speaking with Jurgen Klopp at Liverpool and visiting Burnley, Manchester City and Huddersfield Town.

"I know what I would do if I started again," he added. "Would I want to go back again? Of course I would. And now if I had to do it I would find it 100 times easier.

"I don't think I am going to get such a big club like Celtic again. If I came back to British football it would be a smaller club. But I have done it before. I know what British football is about now. I know the culture and I would be much more comfortable if I went into a similar situation.

"In my eyes, I wasn't a failure. And also, if you look at the Scandinavian people, only one man has lasted more than two years in British football and that was Sven Goran Eriksson. And there have only been five Norwegians - the others are Ole Gunnar Solskjaer, Stale Solbaaken, Henning Berg, and Egil 'Drillo' Olsen. They all only lasted one year so I lasted twice as long."