NEIL LENNON has been a boss for 133 games.

In his short but turbulent time in charge, he has never faced a bigger test of his managerial skills.

Sending out a side to take on Barcelona at any time is a challenge.

Doing so when the Nou Camp side are enjoying the best start to any season in their trophy-laden history, and when you have a clutch of your most important players out or extremely doubtful raises the bar to an altogether different level.

However, if Lennon is wearing the look of a disappointed man even before ball is kicked, it is because he feels for the players who will miss out on what is potentially the biggest game of their career, not because he is already accepting the task is too great.

Lennon lives by the motto that you never know what might happen in football. He has been involved in too many upsets to think otherwise.

He was part of the side which crashed 5-0 in Bratislava for the club's worst defeat in Europe, then, a year later, beat Manchester United to reach the last 16 of the Champions League for the first time in their history.

Not that the man from Lurgan will leave anything to luck or fate. His planning for tonight's long-awaited match has been meticulous.

It's just a pity all that preparation could go out the window if Georgios Samaras joins Emilio Izaguirre, James Forrest, Lassad Nouioui and, most probably, Gary Hooper on the out-of-action list.

That will test Lennon's nous even more. Can he rebuild the formation, tweak tactics and re-deploy personnel in a manner good enough to put a spoke in the Barca machine?

"How do you solve a problem like Barcelona?" Lennon asked out loud. "You have to play at your very, very best, with full concentration and full intensity.

"Sometimes, even then, that is not enough.

"But if we can get something out of the game it will give us a really strong foothold in the group."

If he can pull this off, he will deserve to be placed up there alongside Martin O'Neill and Gordon Strachan in terms of achievement on the European stage.

While in itself a win tonight would not guarantee Celtic a spot in the last 16, it would elevate their profile to a level not enjoyed for far too long.

Lennon showed he has learned quickly by almost grabbing a point in the Nou Camp, only a last-minute lapse of concentration denying him and his players a result they had worked so hard to grab.

But that bitter experience has been put to good use, and the knowledge that for so long they had enough about them to combat the pass-and-go game – of which Barca are the world-renowned masters – will allow them to take the field in front of their own vociferous support carrying a self-belief which could not have been part of the kit they carried with them to the Nou Camp.

Sure, the victory in Moscow on matchday two lifted their spirits because the away-day blues had finally been remedied.

But trying to contain the finest team on the planet – an opinion shared by Lennon – poses questions which can only be answered when you enter the exam room.

If this Celtic side are to graduate with honours, they must build on the good parts of their Nou Camp performance and eradicate the errors which ultimately cost them pass marks.

Fraser Forster – buoyed by his breakthrough to the England squad – will, once again, be a key player. But the men directly in front of him, and those in front of them, will also have to play to their absolute optimum.

Anyone falling below that level risks bringing the entire team down because Barcelona will show no compassion, only a killer instinct.

Lennon's pre-match team talk will focus on what his players do well, and attempt to gloss over what Barcelona do par excellence.

Respect for their ability will be integral to his game plan, but it will not cross the line into fear and awe.

The support will have a vital role to play as they are not accustomed to watching their team chase the ball like a terrier feverishly in pursuit of a bone.

That will happen tonight, but it is no cause for alarm. It is simply what Barcelona force opponents to do, and what they did against Celtic in Spain.

Lennon said: "We will concede ground and the ball at times because they are the best in the world at keeping possession.

"They have proved that consistently at the highest level for the last seven or eight years."

The key is to ensure Barca are playing in front of you, not through you and, when you do get possession, you make maximum use of it.

Lennon came under fire from some quarters for what were perceived as negative tactics in the Nou Camp, but remains unrepentant.

He said: "We played very well in Barcelona, despite what some people thought of the performance.

"At times in the games against Real Madrid and Chelsea, it was 80% in favour of Barcelona. It's what they make you do.

"We can't go too gung-ho or make the game open because Barcelona will pick us off, as they have done to many teams."

As in the Nou Camp, set-pieces will be very important as Barca do have a weakness, and it is the centre of their defence, even when, unlike tonight, it is at full strength.

But above all, discipline and focus must be the watchword. Anything Barca get they must be made to earn.

It could be a night for new heroes in green and white, just as previous jousts with Barca have produced.

"Our record is good here, and the crowd will inspire the players and I am hoping they do themselves justice," said Lennon.

What is already certain is it is a night when players – and the manager – will learn so much about themselves, how far they have travelled, and how far they still have to go.