RONNY Deila was last night warned he faces the prospect of being sacked as manager of Celtic if he fails to secure qualification for the knockout rounds of the Europa League this season.

The Scottish champions will play in their first Group A match when they take on Dutch giants Ajax in the Amsterdam ArenA on Thursday night.

It will be difficult for the Parkhead club, who were knocked off the top of the Ladbrokes Premiership on Saturday when they lost 2-1 to Aberdeen at Pittodrie, to secure a result over in Holland.

And with Fenerbahce of Turkey and Molde of Norway also in the section, there is no guarantee Celtic will finish in the top two and progress to the last 32 like they did last season.

However, Ramon Vega, the former Celtic centre half who now works in finance, believes Deila must keep the Glasgow club in Europe beyond Christmas in order to hold onto his job.

He feels the 39-year-old has to prove to the Celtic hierarchy he is capable of leading them into the lucrative Champions League group stages at the fourth time of asking next year.

Despite the domestic success the ex-Stromsgodset coach has enjoyed since being appointed, his side have lost to Legia Warsaw, NK Maribor and Malmo in the qualifying rounds of the continent’s premier club competition.

It was estimated the 4-3 aggregate defeat to Swedish champions Malmo in the play-off round last month cost Celtic in the region of £13 million in lost revenue.

Former Switzerland internationalist Vega, who is now involved in asset management and real estate acquisition, predicted he has to excel in the Europa League to convince his employers his is the right man to take them forward.

“The pressure is always on the manager,” he said. “Unfortunately for the manager, you are the only one the pressure is on. At Celtic even more.

“Doing well in Europe is pretty much essential for Celtic. It is the financial impact it has at the football club. It is very important the manager gets it right. Otherwise Celtic Football Club or the CEO has to look to something else.

“You have a problem if he doesn’t qualify for the knockout stages. Are you going to stick with this manager until the end of the season if he doesn’t go through in the Europa League? Can they be confident he will qualify for the Champions League next season?

“Or do they say: ‘S*** happens! We trust him. He might qualify’. That is the risk in football. That is the risk a board member or a CEO has to take. But they need to make the decision.”

Vega continued: “If it’s not happening, as is the case at any major company, any big organisation, like BT, Esso, RBS, Barclays, whatever, the chief executive would be sacked. The minute there is trouble they are gone.

“If you compare the companies they are at the same level. They are public companies. You have to be responsible for the sums of money involved.

“Around 30 or 40 years ago that wasn’t so much the case. You had local players and you were just trying to keep the locals happy. Now there is an international XI, the money is greater and the pressure is higher.”

Vega only spent around half a season at Celtic; he was loaned out to them by Spurs midway through the 2000/01 campaign after Martin O’Neill had taken over as manager.

However, after scoring two goals on his debut in a 6-0 demolition of Aberdeen at Parkhead, he enjoyed one of the most successful spells of his professional career.

He helped O’Neill’s men beat Rangers on three occasions – during which they scored seven goals and only conceded once – and win just the third Treble in their history.

The ex-Grasshoppers, Cagliari and Watford player only experienced defeat twice – in meaningless end-of-season league games long after the Scottish title had been won.

So Vega, who failed in a bid to buy Portsmouth when they experienced serious financial troubles back in 2009, knows exactly what is required of a centre half at the club.

He has told new signing Jozo Simunovic, the 21-year-old who Deila is set to hand his debut to over in the Netherlands, and Dedryck Boyata that they must perform straight away despite their tender years.

“In our day, the good times were 28 or 29 years old, whatever position you were, a striker, a defender, whatever,” he said.

“That was just the mentality, the time we were living in. We matured a little bit later. But I think in football today that is nonsense frankly. When you are 22 or 23 you are already mature at international level.

“I would argue that by 23 or 24 today you need to be top end because of the change of attitude and mentality towards youngsters. It is completely different to in the past. I see the younger generation coming through the ranks and by the time they’re 21 or 22 they’re already top players.

“The football industry has changed in the last 20 years. We have academies and youngsters coming through. The infrastructure which is there to support youngsters compared to what we used to have is huge.

“They should be able to perform in Europe despite their age. Now they can only get better. There is no point signing a 24-year-old centre half who is not experienced. It is what he has done in the last eight or nine years.

“To be there at 24 with Celtic you need to have been performing at a high level somewhere else and be a good player. Otherwise you’re not a Celtic player, simple as that. To get to Celtic you need to be the finished product. You will only get better because you have got better players around you.”