The biggest game of the season so far, and a clash between – possibly – the two best teams in Europe at the moment.

The first thing to consider is the mentality of Jose Mourinho. One point clear of Barcelona going into the game, it’s entirely likely that he would take the draw if it were offered to him now. His previous trip to the Nou Camp saw his Inter side defend solidly for the entire game with little or no attempt to get a goal (granted, with ten men, and a two-goal advantage going into the second leg), which shows he knows how to stop Barcelona playing.

That is not to say that this will be anything like as defensive a display from Real Madrid, but we must consider the prospect that they will play for a draw.

Change in shape for Real?

With this in mind, Marca has reported this week that Mourinho will ditch the 4-2-3-1 system he’s favoured so far this season, in favour of a system with a third defensive midfielder. The player to make way here would probably be Mesut Ozil, with Lassana Diarra coming into the centre of the pitch.

It’s unlikely Mourinho would deploy three ‘flat’ holding midfielders, however, and his next decision would be whether to play the third midfielder deeper than the other two, ready to pick up Lionel Messi when he drifts into deep positions, or to play a midfielder higher up the pitch, closing down Xavi Hernandez, the man who dominated the clash between these two back in April. The nature of Diarra would suggest it would be the former. A more surprising move would be to use Ozil as a false nine, as discussed by Roberticus.

Key area

The major battle here looks to be down Barcelona’s right-hand side. The teams who have come to the Nou Camp this year and fared relatively well have made sure they played left-sided midfielders comfortable of tracking Daniel Alves into deeper positions. That was true in Hercules’ shock win early on this season, where Royston Drenthe played on the left of midfield, and a similar pattern emerged in Valencia’s first-half dominance, where two left-backs – Jeremy Mathieu and Jordi Alba – were used in tandem (and to a certain extent in Inter’s performance, where Cristian Chivu started as the left-sided midfielder). In Cristiano Ronaldo, Real’s left-winger is clearly a different breed of player.

He is, however, also Real’s biggest attacking threat. How would a Ronaldo v Alves battle pan out? Ronaldo’s brief this season is to stay high up the pitch and focus on pinning the opposition full-back back. It is unlikely that Alves would be subdued as easily as this, but if he pushes forward this will force Gerard Pique over, potentially exposing him to 1 v 1 situations against Ronaldo, 2 v 2 when you consider Gonzalo Higuain and Carles Puyol.

Barca compromise?

Guardiola is usually not fussed about leaving so few defenders back, but surely against Ronaldo, the toughest individual Barcelona will face all season, there must be some level of compromise.

A possible solution to the problem is to make Barca more secure on the other side of the pitch. Guardiola has three options at left-back – Eric Abidal, Maxwell and Adriano. Abidal is the one most comfortable in central positions, and using him tucked in on that side would mean that Alves would be free to get forward, and Barcelona could briefly shuffle across into a back three with Pique right, Carles Puyol central, and Eric Abidal on the left of the three.

This is broadly what happened against Sevilla, in Alves’ most attack-minded display of the season so far, and would mean that Barca remain 3 v 2 at the back, keeping a spare man that is surely crucial against Ronaldo. Another option is to use Busquets in a deep role, like against Atletico, although this is unlikely.

Other decisions

Real are likely to react to Barcelona’s shape more than vice-versa, but don’t rule out a tactical surprise from Guardiola, perhaps with a more defensive team than usual. In the Clasico back in April, for example, Guardiola used Dani Alves in an unfamiliar right-sided midfield role to help double up against Ronaldo. That is probably less likely to happen here, but it’s not inconceivable that Guardiola, like Mourinho, could opt for an additional holding midfielder – Sergio Busquets will start but could be joined by Seydou Keita or Javier Mascherano. Keita would probably be the favourite, on the left side of a midfield triangle, since he is capable of pressing high up the pitch and closing down Real’s central midfielders. This would then push Iniesta into a forward role and mean Pedro moves to the bench.

That could have ramifications upfront. When Pedro, Messi and David Villa are used as a three, it’s been common in recent weeks for Messi to play as the centre-forward, with Villa cutting in from the left. Villa is less comfortable doing that from the right, so he would play central and Messi would move out to his more traditional right-sided role. This could be the best place for him in this game – if Real are trying to pack the centre of the pitch, and Marcelo (of whom there are still question marks defensively) is being left exposed by Ronaldo, Messi will prosper on the right-hand side of the pitch. Alternatively, Iniesta could be used on the right – a position he rarely plays, but he has started there before this season.

Real will sit deep and Barcelona will dominate possession. Guardiola’s side will probably have no unusual plans in terms of what they do with the ball, but Real are likely to play direct football on the counter-attack to exploit Barca’s high line.

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