Seldom a man to call a spade a gardening implement, Chris Sutton’s assessment of the space which Celtic seem to inhabit these days met with little resistance.

Posting on social media after an impressive display at Fir Park had been followed by a first half no show away to Benfica, the former Parkhead striker labelled Martin O’Neill’s outfit ‘flat-track bullies’.

It felt as apt a description as any to summarise the way of things for long enough in Glasgow’s East End.

Sutton’s old club have bagged 14 titles in 15 years. Notwithstanding the standard of opponent they faced in the Estadio da Luz, the feeble display which was served up in the opening 45 minutes could have come from almost any one of the resultant European campaigns.

This, fundamentally, is the main source of discord for so many supporters. When a club with such a proud European tradition as Celtic dominates domestically, it does not feel unreasonable for it to make an appreciable impact when another crack at continental competition comes along.

There is an acceptance among most supporters that clubs from out-with the major leagues now have the devil’s own job to make the latter stages of the Champions League. There is, though, still a fundamental belief that more could be done to at least give it a try.

Two years on from doing just that in UEFA’s premier tournament, Celtic are struggling for relevance in the Europa League.

Back to back losses to Ferencvaros and Benfica sees O’Neill's men presently sitting in 33rd place of the 36-team group. To stand any chance of yet qualifying for the knockout round, a win against Celta Vigo feels non-negotiable.

If a long-overdue performance in Europe doesn’t arrive on the back of Sunday’s superb display against Hearts, you suspect it’s going to be a long time coming.

Whatever accusations can justifiably be levelled against the hierarchy for another underwhelming transfer window, though, the football Celtic produced in that 7-1 trouncing suggested that the squad still contains considerable quality.

Bluntly, it should have had enough to see out a four-goal lead in Linz against LASK. It still had the capacity to defeat Ferencvaros in Glasgow. And it should at least have made Benfica work harder for their victory last week.

For all the finger pointing and the hand-wringing, it’s certainly better than it has shown itself to be in the past three European matches.

Something has been missing. Tonight would be quite the time to locate it.

‘We definitely have to figure out a few of the structural things in terms of being without the ball, what suits this team and all the players within it and then just a full commitment from everyone to defend,’ offered assistant manager Shaun Maloney.

‘I think we’ve got really talented players as, I think, the weekend shows, and the second half against Benfica.

‘It sounds really simple. But if we do that (be better without the ball) then I think we can be a pretty good side.

‘We’ve shown it already this season that we can be.

‘We’ve also shown that when we aren’t quite at the same levels without the ball then we can get hurt against any side.’

When broadly the same group of players can look so impressive in a league match yet so lost in Europe, a wide sweeping conclusion is drawn.

That it’s not the system that’s the issue. That it’s the players themselves. It’s a theory which Maloney refutes.

‘I think in these types of moments, it’s also on us as coaches to help them find better answers on the pitch,’ he added.

‘I definitely wouldn’t sit here and say it’s fully on a player’s commitment or work rate. I think it’s everything. I think we have to be better as coaches.

‘The players have to be more consistent. It’s a group thing, really. I think that was one of the great things about the international break.

‘We got to sort of stop and sort of see how those first nine, 10 games went.

‘There were moments when we were really, really good with the ball and then there’s moments where we’re not at the level without the ball.

‘I think that’s what I’ve really liked the week that we’ve came back.

‘We had a period against Benfica where they were a really good side. I think when there’s things that are slightly wrong, they really hurt you.

‘But without the ball against Motherwell, without the ball against Hearts, it felt more like Celtic of the past few seasons. I think it’s our job to try and create that again tomorrow.’

The identity of the architect of Celtic’s current style of play is also, curiously, the subject of some debate right now.

With 74-year-old O’Neill assisted by a raft of coaches little more than half his age, the theory is that the veteran’s authority in all matters isn’t as absolute as it once used to be. This suggestion is met with a wry smile.

‘I think anyone that’s written or said that, I don’t think they’ve ever worked with Martin,’ said Maloney.

‘I have no idea why somebody would say that. If they came and watched us each day, Martin leads everything - recruitment, team selection, tactical. I think Martin’s actually said this.

‘I don’t know why anyone would even think that without working with him. So, yeah, that would be incorrect.’

That said, this is a fixture which evokes memories of O’Neill in his pomp. The first leg of the UEFA Cup clash in 2002-03 saw the Northern Irishman sent to the stand by referee Claude Colombo with the Celtic manager later accusing the official of pushing him.

Having won the first leg through Henrik Larsson’s goal, Celtic prevailed on away goals in Spain after John Hartson netted in a 2-1 loss.

‘I don’t remember that (O’Neill sent off),’ said Maloney. ‘I remember John scoring away.

‘It does feel like a lifetime ago.’

The historical significance of that win was huge. With progress beyond Christmas in Europe secured for the first time in 23 years, by the end of that storied season, Celtic returned to Spain to take on Jose Mourinho’s Porto in the final in Seville.

The revamped European calendar means Celtic will have continental matches to play in the New Year, regardless. Ensuring that there’s something riding in them is imperative.

‘We need to start getting points really,’ said Maloney.

‘I think we have shown in certain away games that we can produce a performance to win.

‘Generally in these competitions, the home games will determine whether we ever make it into the second stage, like we did last year. It’s a really big game.’