Barcelona welcome eternal rivals Real Madrid to Camp Nou on Sunday for what will be the 237th Clasico and the build-up to the game has been dominated by a question of respect.
The Blaugrana are already La Liga champions, having wrapped up the title with a 4-2 win over Deportivo La Coruna, and tradition dictates that Madrid honour their rivals with a pasillo ahead of the game.
However, the capital club are refusing to do so, a decision that has sparked debate and bemusement among supporters and players alike.
But what exactly is a pasillo? Ahead of the game, Goal takes a look at what all the fuss is about...
What is a 'pasillo'?
Pasillo is the Spanish word for a guard of honour in a sporting context in which one team acknowledges the achievement of the other.
Generally speaking, the tradition is reserved for teams who have won domestic league titles, such as La Liga or the Copa del Rey in Spain.
Since Barcelona have already won the league, Real Madrid are expected to acknowledge that fact with a pasillo, just as Deportivo did following the Catalan club's Copa del Rey triumph.
Literally translated as 'hallway' or 'corridor', it is essentially formed by the players of one team, who stand parallel in two rows facing each other while their opponents pass through as enter, or leave, the field of play.
In many cases those forming the guard of honour give the team they are paying tribute to a round of applause, but this is, understandably, absent during more solemn occasions.
In the Champions League final, the losing team is traditionally honoured with a pasillo after the match.
The victors line up either side of their vanquished opponents, offering commiserations as they make their way to collect their runners-up medals.
Why won't Real Madrid give Barca a pasillo?
Real boss Zinedine Zidane says that the decision not to honour Barcelona with a pasillo in their Clasico meeting on Sunday was made by him.
Back in April, the French coach explained to reporters: "It is my decision and that is it... Barcelona broke the tradition."
Zidane's claim that Barcelona were the first to dispense with the custom references last December's Clasico encounter at the Santiago Bernabeu, which Madrid lost.
Back then, Madrid had just won the Club World Cup but Barca did not acknowledge their rivals' achievement with a pasillo on that occasion and it has evidently irked the Blancos boss.
There has been a lot of discussion about the issue since, with pundits debating whether or not the tradition should be observed, but the players do not appear to be heavily invested.
Barca star Gerard Pique, for example, offered a jocular response by mockingly suggesting that he would lose sleep over Zidane's decision.
Pique's opposite number Sergio Ramos, meanwhile, said that "too much fuss" was being made over the issue. The defender remarked: "Barca have the title, which is what they wanted, but there will be no guard of honour full stop."
Barca head coach Ernesto Valverde has insisted that his club and players did recognise their rivals' achievements, but appeared to back his counterpart's stance, saying that it has "lost the essence" it had in the past.
“A pasillo was something done years ago as a symbolic tribute, as recognition between players, when football had not acquired this nuance that is contaminating everything," Valverde said. “We do have recognition towards Madrid, for what they have achieved this year.
“On the notion of a guard of honour, I wouldn't do it for anyone, nor would I want it to be done for us. It has now lost the essence that it had a few years ago.”
It must be noted that Real Madrid have previously honoured Barcelona with a pasillo in the past.
That occasion came at the Santiago Bernabeu in 1991, when Johan Cruyff's 'Dream Team' swept to league glory.
Have Barcelona given Real Madrid a pasillo?
Yes, Barcelona have done it before, which is one of the reasons why many pundits and supporters have been especially critical of Zidane's position on the matter.
The Blaugrana honoured Real Madrid's Liga triumph at Camp Nou in 1988 and most recently the tradition was observed by Frank Rijkaard's side after Madrid won the league in 2008.
Back in 2008, then-Barcelona captain Carles Puyol admitted that as a 'cule' (affectionate term for Barca fans and players) he did not like it, but said that it was a necessary gesture as a sportsman.
However, recent developments suggest that the custom will not be continued in the future, particularly given Valverde's aforementioned comments on the matter.
Do other countries do guards of honour?
The concept of a guard of honour is, by no means, confined to Spain and other countries do have a tradition of acknowledging the sporting achievement of their rivals.
It is common to see a guard of honour in England's Premier League, for example, when a team has won the league title before the season concludes. West Ham recently gave Manchester City that treatment in their game at the London Stadium.
The custom is not confined to football either, with the guard of honour frequently seen after rugby union matches.
In rugby, however, the winning team applauds the losing team off the field in appreciation of their efforts.