Many have commented that, in an ideal world, this may have been the final of the competition. Barcelona and Inter are generally considered to be the strongest two sides left in the Champions League – and of course, they are also the only two actual champions left.

For the tactical enthusiast, however, a two-legged tie between the two most interesting sides in the competition is a more exciting prospect than a one-off game.

It pits Jose Mourinho – often considered the master tactician – against Pep Guardiola, who in just two seasons has demonstrated that he, too, is a very difficult manager to outwit.

Of course, this is not the first meeting between the sides this season – they were drawn together in the group stage, producing a 0-0 at the San Siro, before Barca triumphed 2-0 at the Nou Camp, with a Pique goal from a corner and a glorious move finished by Pedro.

The goals from that game:

Mourinho was surprisingly gracious after the defeat at the Nou Camp, saying:

“Barcelona are a squad of players who play genuinely well…they play a high intensity game; they press high and very quickly. And when they have the ball they use it with high-speed passing. That is a really speciality. It is easy to say that they are a better team than we are.”

Whilst a repeat of those two scorelines would not be a major surprise, it is perhaps difficult to read too much into those games – the first was the first game of the tournament and was tight, cagey and generally quite dull – the second was played without the two key players on either side – Lionel Messi and Wesley Sneijder – whilst Zlatan Ibrahimovic was also injured.

It’s also interesting to note that both teams have changed their primary formation since their meeting in November. Inter started the season with a 4-3-1-2 shape that saw Sneijder playing ahead of a solid midfield trio (Dejan Stankovic replaced him for that game), whilst Barca were playing with the flexible 4-3-3 that they won last season’s Champions League with.

Now, Inter switch between the 4-3-1-2 and a 4-3-3, or 4-2-1-3, that sees Sneijder deeper in midfield, and two forwards (generally Samuel Eto’o and Goran Pandev) on the wings – and have favoured the latter in recent weeks. Barcelona have had a similar journey – experimenting with a strange 4-2-4ish formation before recently installing it as their main shape, with it working excellently against Arsenal in the last round.

It would be a surprise if Inter didn’t go with the 4-2-1-3 for this game. Against Barcelona it is vital to occupy the opposition full-backs – especially Dani Alves at right-back, and Barcelona dominated the game at the Nou Camp partly because Alves and Abidal were able to come forward into midfield and help Barca retain possession.

Eto’o has generally been used in a wide role in recent weeks, and he could be used on the right-hand side to try and replicate the role Theo Walcott played against Barcelona – staying wide and running at pace. Pandev has been the first-choice player on the left-hand side but has been out of form recently, and Mourinho could go for a more defensive option on the left side of midfield – Dejan Stankovic can do a job there, or Mourinho may go further and play Javier Zanetti or even Christian Chivu on the left of midfield. There has been speculation Maicon could play in midfield – he did well there in the cup against Fiorentina – but it seems unlikely given Barca’s main threat is from the right, not the left.

Sneijder will play in the No 10 role and look to occupy Busquets, whose passing against Arsenal was excellent, with Esteban Cambisso joined by Zanetti (unless he is deployed elsewhere) or Barcelona youth product, Thiago Motta.

The key to nullifying Barcelona is surely to stop Xavi playing – Arsenal failed to do so and lost, Real Madrid failed to do so and lost – but Mourinho will not make the same mistake. Motta may be given the job of tracking him.

Barcelona’s selection dilemmas start from the front. Zlatan Ibrahimovic would love to get another run out back at the San Siro, but he has only played eight minutes (in Barcelona’s weekend draw at Espanyol) of football since his two goals at the Emirates, and he may not be 100% fit.

Barcelona might be better off playing without Ibrahimovic. Opinions remain divided on the enigmatic Swede, but even his admirers admit that he forces Barcelona to play in a slightly different way – he is less mobile than other forwards in the side, and is plays more of a traditional striking role than Pedro, his most natural replacement.

Inter’s centre-backs – Lucio and Walter Samuel – are utterly dominant in the air but prone to small, quick, tricky players. They marked Didier Drogba out of the game both home and away against Chelsea, and recently against Fiorentina faced more problems against the youthful energy of Keirrison than the strength and aerial presence of Gilardino. Ibrahimovic is far from a one-dimensional player, but Guardiola may decide that a line-up without him might be the best way to get at Inter – really testing the ageing centre-backs by playing no out-and-out striker.

It would make sense for Barcelona to play a team similar to the one against Real Madrid in the second half, where Maxwell was pushed into a left-sided midfield position to track the runs of Sergio Ramos – here, he could do the same against Maicon, with Eric Abidal behind him. Guardiola could consider bringing in Gabriel Milito to mark his brother Diego, and play Puyol at left-back.

Almost an entire preview without mentioning Messi – how do you stop him? Man mark? Double mark? Mourinho’s theory will be fascinating. His experiment with an ultra-defensive 5-4-1 formation once Inter had taken a 0-1 lead over Fiorentina in the cup was also interesting – would he try something similar if Inter go ahead?

A near-impossible task to try and predict the line-ups, but that’s what makes the game so fascinating – in Mourinho and Guardiola we have two tactical chameleons who are happy to adapt their shape according to the opposition. We might be set for a footballing chicken game.

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