On the face of it, it looks like Mission: Impossible for Celtic in Barcelona tonight.
This current Barca side are unquestionably one of the greatest teams of any era, and there is an undoubted gulf in class between the two squads.
Yet there are some who dare to hope that Celtic might just take something from the match.
Just what is this extremely cautious optimism based on?
First of all, Barcelona have a perceived defensive frailty going into the game.
On Saturday, they conceded four in a thrilling match away to Deportivo la Coruna.
Typically, Barca still won, with Lionel Messi’s 21st hat trick for the club pivotal in a 5-4 victory.
It should be noted, too, that of Deportivo’s four goals, one was a penalty and one an own goal.
Barcelona also played for 43 minutes with only 10 men after Javier Mascherano was ordered off at the beginning of the second half.
Maybe not too much call for optimism, but there is also the small matter of a mini defensive crisis for the Catalans.
They will be missing captain Carlos Puyol, Gerard Pique, Dani Alves and Eric Abidal. Midfielders Alex Song and Mascherano look set to play in central defence against the Glasgow side.
Lionel Messi is in the form of his life and has destroyed better defences than Celtic’s almost single-handedly with stunning regularity over the past few seasons.
It’s not all about Barcelona, though.
Celtic are showing signs of having clicked into gear in recent weeks and have been buoyed by their first-ever away win in the group stages against Spartak Moscow three weeks ago.
This is a very different Celtic side from the one that reached the last 16 two years in succession under Gordon Strachan.
Where Strachan’s side were well-drilled and hardworking but (aside from Shunsuke Nakamura) somewhat staid and predictable, Neil Lennon’s team is, in comparison, bristling with creative talent.
There is a solid-looking spine to the team, of recent England call-up Fraser Forster in goal, Nigerian internationalist Efe Ambrose in central defence, Kenyan powerhouse Victor Wanyama in central midfield and the free-scoring Gary Hooper in attack.
Much will depend on how those four perform on the night.
Forster is increasingly commanding in goals but was at fault for Spartak Moscow’s second goal on Matchday 2.
Ambrose is quick, strong and powerful but has shown a tendency to over-elaborate under pressure at the back where a punt into the stands would be a more sensible option.
Wanyama, at SPL level at least, is the complete footballer and shows every sign that he could be a top-class player at a much higher level. He does, though, still tend to find his name in the referee’s book due to rash tackles, and at Champions League level, that could be disastrous.
Hooper has so far met every challenge presented to him at Celtic and has scored goals at every level.
Around this spine, and subject to availability, Celtic have players who might—just might—prove to be capable of springing a surprise on Barca.
Emilio Izaguirre and Adam Matthews are fast, skillful fullbacks, while Kelvin Wilson has been slowly rehabilitating himself this term with a series of solid performances, notably alongside Ambrose.
Joe Ledley, Beram Kayal and Scott Brown (if fit) will vie for the midfield berths alongside Wanyama. The steadiness and goalscoring threat of Ledley may be preferred to the more energetic but sometimes erratic Kayal, while Brown will definitely play (fitness permitting).
In attack, Hooper will probably be supported by Georgios Samaras, who has been outstanding this season, especially in the Champions League. His pace and strength will be utilised at every opportunity, possibly from a position wide on the left.
It will be a huge bonus for Celtic if Kris Commons is able to play. His ability to pick a killer pass and his eye for goal will be vital for the team this season, regardless of results in the double-header against Barcelona.
Apart from the obvious—Barcelona’s off-the-ball movement, Xavi and Iniesta’s quick, intricate, bewildering passing and Messi’s outrageous genius—the biggest problem Celtic will face tonight will be Barcelona’s relentless pressing on the rare occasions Celtic have the ball.
Celtic won’t get a second to settle on the ball and will have to work very hard to avoid losing possession high up the pitch.
Probably Celtic’s best chance tonight will come from set plays. This is a tall, strong and physically imposing team, and one that could exploit the makeshift nature of Barcelona’s smaller defence.
Going Route 1 and bypassing midfield altogether could be Celtic’s best chance of taking the game to Barca and putting pressure on them at the back.
There are signs that Celtic’s current crop of players are the best seen at the club since the Martin O’Neill era, and they are certainly higher in quality than Gordon Strachan’s overachievers.
Tonight will provide the opportunity to assess just how good they can be.
Looking back at the history books, Celtic have played at Camp Nou three times in the past decade, gaining a 0-0 draw to knock Barcelona out of the UEFA Cup in 2004, a 1-1 group-stage draw in 2005 and a 0-1 defeat in the last 16 stage in 2008.
Barcelona has actually scored more goals against Celtic at Celtic Park than in Camp Nou.
While the current Celtic side has more attacking options than the last two to visit Barcelona, they have not yet achieved the defensive solidity of those earlier sides.
IF the Barcelona defence has an uncertain night, and IF Celtic’s midfield can make any sort of impression on the game and IF Celtic’s big players can reach the standard many suspect that they can, then anything is possible.
Perhaps the best that Celtic can hope for tonight is to come away without being embarrassed, but the opportunity is there for at least some of a very talented group of players to make themselves legends.