On Friday, Shakhtar Donetsk beat Illychivets 3-1 to preserve their 12-point lead at the top of the Ukrainian Premier League. They have played six times since the winter break – two of those games against Roma in the Champions League – and won five, the only blemish being a surprise defeat at Karpaty Lviv. They are in form, not quite at their very best, perhaps, but close enough to it to suggest a return to true fluency is imminent.
And yet ahead of Wednesday's game against Barcelona, such details feel trivial. This is like John Lambton taking on the Worm; the task feels of a magnitude so vast that past record against mortal opposition is barely relevant. There is need not merely of great courage and ability, but also of some act of great cunning. As Pep Guardiola acknowledged last week when he referred to him as "a wily old cat", if anybody is capable of an unexpected strike of tactical genius, it is Shakhtar's veteran coach Mircea Lucescu.
If the Romanian plays it straight, this could end up as a re-run of Barcelona's tie against Arsenal in the last round: two sides with similar philosophies, one of whom is sufficiently better than the other to win comfortably. Lucescu has always espoused a philosophy of open, attacking football. He prefers young players he can mould – those "without the fear of age" – who will play his high-risk brand of technical pass-and-move football. His sides operate with a high offside line, his full-backs are auxiliary wingers and his front-line is highly fluid. Shakhtar's style and Barcelona's are virtually indistinguishable.
Where they differ is in shape. Barça tend to operate either a 4-3-3 or a 4-2-1-3, while Lucescu, after a decade or more of playing with a midfield diamond, has over the last three years become a convert to 4-2-3-1. Theoretically at least, that could cause Barcelona some problems, as it has on the last two occasions the sides have met.
In December 2008, Shakhtar won 3-2 at Camp Nou, but that was an end-of-group-stage game in which Barça fielded a significantly weakened line-up. More relevant is their meeting in the European Super Cup in Monaco in 2009 with what were near enough full-strength teams (Barça: Valdés; Alves, Puyol, Piqué, Abidal; Touré, Keita; Xavi; Messi, Ibrahimovic, Henry. Shakhtar: Pyatov; Srna, Kucher, Chyhrynskyi, Rat; Hai, Hübschman; Willian, Fernandinho, Ilsinho; Luiz Adriano).
Barça did win on that occasion, but only with a Pedro goal five minutes from the end of extra-time. If Messi plays as a false nine dropping deep away from the Shakhtar centre-backs, he will be moving into an area occupied by two holding players. They will, admittedly, also be covering for Shakhtar's two highly aggressive full-backs, Dario Srna and Razvan Rat, and looking to close down the breaks of Xavi and Andrés Iniesta, but it won't be easy for Messi to find space in that area 20-30 yards outside the penalty area.
It's far from clear who Lucescu will pick as his two holders. Fernandinho and Henrikh Mkhitaryan occupied the positions on Friday, but that was the Brazilian's first game back since breaking his leg against Obolon in September while the Armenian is 22 and has only ever started four Champions League games. Both, anyway, are passers rather than destroyers, so it seems likely that one or possibly both of Oleksiy Hai and Tomas Hübschman, more defensive presences, will be preferred.
The attacking-midfield three will also have to do its share of defensive work because, technically gifted and comfortable on the ball as Shakhtar are, it's hard to imagine how they could dominate possession against Barça. Unless Mkhitaryan is used on the right to provide a more naturally defensive presence against Maxwell, all three are likely to be Brazilian: probably Douglas Costa, who has come of age this season, to the right, Jadson in the centre, and Willian, rumoured to be a target for Chelsea and Liverpool, on the left. Luiz Adriano is a mobile centre-forward and his movement, although he doesn't drop anywhere as near as deep as Messi, could trouble Gerard Piqué and Sergio Busquets (or Carles Puyol if he recovers fitness in time). "The Brazilian players they have, the four young guys, are very good," said Guardiola.
If he recovers from an ankle injury, Dmytro Chyhrynskyi, the Shakhtar centre-back, may feel he has something to prove after a disappointing move to Barcelona. He joined them after that Super Cup game for £22m, but managed just 10 starts before returning to the Donbass. With Oleksandr Kucher still recovering after knee surgery, he is likely to be partnered by the highly impressive 21-year-old Yaroslav Rakytskyi, a player who joined the club as a 14-year-old and tends to be wheeled out whenever Shakhtar want to counter claims that they only buy talent and never develop any of their own.
The real key to the game, though, is the battle of the full-backs. If Dani Alves didn't exist, Dario Srna might be recognised as the best attacking right-back in the world. On Wednesday, it is his job to drive Maxwell back, to support Douglas Costa and to help Chyhrynskyi handle David Villa. On the left Rat has a similarly tripartite job, trying to handle Pedro and to support Willian against Dani Alves. Barcelona's full-backs, of course, will face similar difficulties should Shakhtar enjoy a spell of possession.
The question then becomes how far Lucescu withdraws his wide-men. He could do what Fabio Capello did in Zagreb in World Cup qualifying in 2008 when he played Theo Walcott high on the right to check Danijel Pranjic's forays. The left-back, wary of allowing a player of such pace behind him, became tentative about his forward surges, and the structure of Croatia's left side was lost as England won 4-1. The danger is that the full-backs just push forward anyway, relying on their side to dominate possession, leaving a team defending a man short. Manchester United were the victims of that against Real Madrid in 2003, when Roberto Carlos hurtled down the left as though David Beckham didn't exist, leaving Gary Neville horribly exposed in a 3-1 defeat.
Convention says Douglas Costa (or Mkhitaryan) and Willian should play deeper in the first leg and be more adventurous in Donetsk (particularly given the way Arsenal eviscerated Shakhtar at the Emirates in September) but Lucescu is anything but predictable.
The biggest advantage Shakhtar have is that nobody expects anything of them. "We have already achieved our goal, by making it through to the last eight," Srna said. "This is a great success. Now we are facing the following task: to overcome the best team in the world. Personally, I think Barcelona are the best team in the history of football. Therefore, we do not feel any pressure; we can go on the pitch and just play football, which is an unusual situation for Shakhtar."
They may also profit from the calendar. Teams from eastern Europe, who have a long winter break and either a season that runs March-November or, as in the case of Ukraine, July-May with a very short close-season, tend to suffer from fatigue in late autumn, when the key games in the group stages of the Champions League are played, something seen in the disproportionate number of late goals they concede in those matches.
Come the spring, though, once the rustiness of the winter-break is out of their legs, eastern teams should be fresh while western opponents suffer tiredness. That in part explains why eastern sides seem to perform so much better in the Uefa Cup/Europa League than in the Champions League; once they reach the knockout stages – which is easier to do in the lesser competition - they have an advantage of fitness. The pressing game employed by Barcelona and Shakhtar is exhausting, and it may be that Shakhtar can employ theirs with a fraction more sharpness than Barça.
So, will Shakhtar win? If Srna and Rat win the battle of the full-backs, if Shakhtar's two holders can stifle Messi, if they can find an away goal, if they can restrict Barça to no more than a one-goal lead, then perhaps they could upset Barça in the feverish surrounds of the Donbas Arena. It remains, though, a slim possibility: Shakhtar are a very good team, but Barça are a fewer levels beyond that.