It is hard to exaggerate the significance of Ajax’s visit to Celtic Park tonight for Ronny Deila.

The reputation of Celtic’s Norwegian coach is sorely at stake in Europe. In this Europa League campaign Deila is running out of time to prove that he can cope with and adapt to the higher demands of football.

Defeat – and even a draw - for Deila is unthinkable. It would leave Celtic floundering in Group A and only add to the impression that their coach is out of his depth in anything beyond the domestic fodder of Scotland.

Deila’s record in Europe so far with Celtic is poor. Of the 12 matches he has completed at group-stage or better his record reads: Won 2 Drawn 5 Lost 5.

If you want to throw in four key play-off matches to that mix – against Maribor and Malmo – it only looks worse: Played 16 Won 3 Drawn 6 Lost 7. And this is to ignore two hammerings from Legia Warsaw last season before a registration breach by the Poles rescued Celtic.

Deila desperately needs to send out a signal against Ajax that he is equipped to meet the higher European challenge. The Dutch “giants”, like Celtic themselves, are no imperious European power. They should be distinctly beatable on home turf.

Deila forever offers hints that he can do it. Celtic played well in drawing 2-2 with Ajax in September, and there have been stirring moments against Inter Milan and Fenerbahce which hinted at something better.

But the long evidence points to a coach who has so far failed to make the step-up. Deila’s Celtic on this stage have struggled forlornly to live up to the club’s historic reputation.

Of course, Deila and Celtic’s difficulties require a wider context. The recent recruitment by the club, and willingness to part with money, has looked flawed.

Other than Leigh Griffiths as an attacking spearhead, what else do Celtic have to offer? Nadir Ciftci came for £1.5m and has looked distinctly ordinary so far. Beyond Griffiths, and the eccentric signing of Carlton Cole, Celtic’s squad is bereft in the final third of the pitch.

The same might be said for their defensive planning this season. When Jozo Simunovic arrived for a reputed £4m in late August it was almost as if Celtic realised they were suddenly stricken in that department.

This Croatian had better hurriedly look the part, because none from Dedryck Boyata, Efe Ambrose or Tyler Blackett does.

Tonight at Celtic Park Deila has his work cut out in other areas. Injury and suspension look like robbing him of four midfielders: Scott Brown, Kris Commons, Nir Bitton and Stefan Johansen.

What do Celtic have in reserve to cope with this?

The impressive Tom Rogic is suddenly integral and essential to Celtic’s aspirations on the night. This might be the occasion, too, when Scott Allan is suddenly unleashed as a Celtic player, albeit in emergency circumstances.

Yet Allan has played eight minutes of first-team football since the end of August. He has simply disappeared into a black hole since his much-chronicled arrival from Hibs.

Allan’s fate – a large part of it being down to injury - seems to fit with a certain chaos invading Celtic these days.

Celtic’s player-crisis will almost certainly mean either Stuart Armstrong or Gary Mackay-Steven – or both – starting against Ajax. Yet neither is looking confident or improved on this time last year. This, too, seems to pose questions of Deila and his approach.

Charlie Mulgrew is also an option for Deila. Indeed, this Celtic team could include Mulgrew, Allan and Ciftci all starting on the night.

Deila goes into this Ajax match with multiple questions being asked of him. The most important of which is: can he raise his team to victory?

He is being damned in some quarters of the Celtic support, where some view him as the time-honoured “dud”. At this stage, just 18 months into Deila’s reign in Glasgow, that seems a harsh opinion.

But Deila, never more so than tonight, has a chance to dismantle that type of thinking. In reputational terms, this is his moment.