Foreboding can be the first instinct when opponents are able to call upon such a devastating variety of talent, but Celtic already have a psychological advantage. "We know what's coming," said the manager Neil Lennon.
He was talking about the threats that Barcelona would pose to his side, but the impact on his own players will also be significant. Having performed with discipline and competitiveness at Camp Nou last season - when Barcelona needed a very late goal to secure a 2-1 win - then defeated the Catalan side in a memorably raucous occasion in Glasgow, Celtic will not be intimidated by the scope of the task they face tonight.
"The experience from last year is fresh," the Celtic manager said. "We will be prepared."
The absence of Lionel Messi through injury will rob the encounter of some of its glamour. Lennon could be flippant in saying that he was disappointed because he wanted Messi's jersey after the final whistle, yet the more prescient response was that Barcelona will be weakened but not debilitated.
They will most likely play Cesc Fabregas in the No.9 position that is, as Lennon remarked, not the conventional centre-forward role that British football recognises, but a free-floating creative presence.
"It was six of one and half-a-dozen of the other, Lennon said of Messi's absence. "I'm delighted for selfish reasons that he is not playing. But for the game itself and the occasion, I'm a bit gutted. Will they be a little bit different? They don't really change the way they play. The only difference is they won't have the wee man.
"Any team would be less effective if they lost Messi. Barcelona are no different. He is huge. But if you look at the games they have played without him, they have won the majority of them anyway.
"I don't know if their pride was hurt by losing here last year. But I know they will be coming highly motivated. They will want to qualify from the group as quickly as possible. There are going to be spells of pressure. And hopefully watching the [DVD on last season's] game again over the weekend will have given the [players] reminders that, yes, we won and yes, it was brilliant, but it was really, really hard."
Celtic's approach last season was based on containment and exploiting set-pieces, with Victor Wanyama scoring the opening goal with a powerful header from a corner kick. The same principles will apply tonight, and Lennon spoke of Barcelona's vulnerability to "physical assaults" and the fact that Valencia scored twice from crosses in a recent La Liga game against Barcelona. His options are limited by injuries to Joe Ledley and Dirk Boerrigter, but then last year's victory was achieved without Gary Hooper and Scott Brown. "You make do with what you've got," Lennon said.
Celtic will be reliant on key individuals. They could be identified by the amount of praise the manager reserved for specific players, with the qualities of Brown, Georgios Samaras and Fraser Forster all dwelled upon. Celtic will expect to be assailed, particularly in the opening period, since Barcelona have often accumulated goals early in games this season. To repeat last season's feat, Celtic will need to be resilient and ruthless.
"We are not going to go toe-to-toe with them and try to play them at their own game because that's suicide," Lennon said. "We will have to play a British-type game. We have to play our way and the best way we can to contain them. We must be in the game for the first 20-25 minutes because they do start games like a house on fire. They can kill you very quickly and we have to be switched on from the start."
The focus, as much as the task, is intense. There is more media coverage for this game than there was for the visit of Juventus in the round of 16 tie last season. After his press conference at the stadium yesterday, Lennon spent time jogging round the pitch, and he is raising money for charity by running in the Glasgow 10k on Sunday, but it might also have been a release from the strategising.
He is a manager in command of every aspect of his assignment. No assumption can be made on the basis of last season's result, but Lennon at least knows that order and commitment to defensive duties, and good fortune in front of goal, can be a powerfully effective combination. The team he selects will reflect that, but highlighting the potential impacts of Samaras, Brown and Forster tells of their critical roles.
"If we are to get something out of the game, I am going to need all of [Samaras's] capabilities - his height, his physical presence, his running power and what I like about him is the longer the games go on, the stronger he seems to get," Lennon said. "He can relieve a bit of pressure with those runs he makes, but we don't want to leave him isolated either.
"You have to have belief. We're used to winning, we're used to dominating games and I have international players who have developed very well over the last 18 months. [Brown] has that maturity and presence about him that all good midfielders have at this level. And when [Forster] really puts his mind to it, he is brilliant at keeping that ball out of the net. I'm going to need him to do that again."
Celtic know the full extent of the task they face, but fear will not enter their thinking. It is a time, again, for boldness and assurance.