Hidden card: three Clasico plans in Mourinho's mind

Fede raised some doubts at the defensive level, but he generally delivers good performances. Valverde played in this position during the second half against Villarreal, setting up a goal for Diomande. He then finished the match against Roma in the same role, and he hasn't let go of it since.

Against Sevilla he lined up at right-back, then again against Leipzig. That's four consecutive matches in the same position. Logic suggests the approach won't change now, least of all before the biggest game of all.

Valverde carries the ideal gift for vertical progression, allowing him to burst into advanced areas. He combines smartly with the midfielders and helps create numerical superiority. His profile hands the team an edge on several fronts.

That choice leaves two spots open: a player in midfield and a right winger.

Mourinho's previous selections tell the story. He likes a left-footed player on the right for the tactical harmony it brings. When that player drifts inside, Valverde can push forward and exploit the spaces.

The competition, then, narrows to three names: Guler, who in theory should be indispensable, though Mourinho dislikes that word, Bernardo Silva and Endrick.

Two of them should start. If Guler and Bernardo Silva play together, one of them takes the right wing. Should Endrick get the nod, one of the others has to drop in alongside Tchouameni in midfield.

That's the crux of it. This scenario looks the most likely for the Clasico at Camp Nou.

But this is not the only option. Another possibility exists: restoring the Valverde and Tchouaméni duo in midfield.

The idea tempts precisely because of the defensive fragility that could surface with a pairing of Güler or Bernardo Silva alongside Tchouaméni.

That is the point worth weighing. The dip in the ability to link the lines is well known to everyone, true, but when the opponent sets out to pin the team back and crank up the pressure, physical strength becomes priceless.

Such a scenario would push Güler to the right wing and hand the right-back berth to Dumfries, who sits ahead of Trent Alexander-Arnold in the pecking order for now.

With that, the Royal club would revert to the setup used most since the start of the season. It is also the setup that has raised doubts on several occasions.

This option would strengthen the right side, with Gordon likely to feature and Karim Adeyemi far from ruled out, while leaving little room for further debate over the rest of the lineup.

Reward players for their level and Güler is the man to partner Tchouaméni in midfield.

Meanwhile, the specialists will carry on battling it out for the right-back berth.

Tactically, Madrid have turned to this method for short spells before, the idea being a constant exchange of positions between Valverde and Güler. One drifts into the centre, the other pushes up the flank, then they swap. Round and round it goes. That endless movement hands the team huge flexibility.

Hand possession to Barcelona and sit in to counter, and this option fits the bill nicely.

The trade-off is a loss of physical steel in midfield. Every option carries its upsides and its downsides.

The other slot is still up for grabs. This one, though, comes down to a straight fight between two players, with no complicated calculations or puzzles to solve.

Mourinho must weigh up what each man offers, then pick the better fit. Huijsen is slightly less solid, yet he is far superior at bringing the ball out from the back and building play. Rüdiger brings greater defensive steel, but he is less assured with the ball at his feet.

Dean Huijsen leads the way on starts so far, with 9 to Rüdiger's 5.

Konaté's place is beyond doubt. He is the defender Mourinho trusts above all, having started 10 matches, with rests handed to him against Malaga and Leipzig.