The last time Diego Simeone was at the Camp Nou, in May, the Atlético Madrid manager was applauded by the home fans. The last time Barcelona’s manager, Luis Enrique, was at the Camp Nou, on Thursday, he was whistled by the home fans. On Sunday night they meet again, seven months on. For Barcelona, there could hardly be a worse opponent: this is a club in crisis with a manager staring into the abyss while behind him they wait to nudge him over the edge

Atlético and Barcelona met six times last season. Atlético did not lose any of them: they knocked Barcelona out of the Champions League and on the final day took the La Liga title. If that run continues, the consequences in Catalonia are likely to be even more dramatic – and they have been dramatic already. This is one of Spain’s biggest games, a fascinating match, yet it has become one where the focus will be on the bench, the directors’ box and the stands, as well as the pitch.

Institutionally, Barcelona have been under pressure for some time but defeat at Real Sociedad a week ago, with Lionel Messi starting on the bench, set the crisis in motion. On Monday, the club’s sporting director, Andoni Zubizarreta, was sacked. Hours later, his assistant, Carles Puyol, walked. An avalanche of stories outlined in painful detail the breakdown in Messi’s relationship with Luis Enrique, who would “not confirm or deny” them in a press conference on Wednesday.

That day, in a long and exhausting press conference of his own, the president, Josep Maria Bartomeu, called summer elections, a year ahead of schedule, in order to “reduce the tension”. It has not worked.

Over 75 minutes, he was on the ropes and, although the following night Barcelona beat Elche in the Copa del Rey, there were just 27,000 in the Camp Nou and, when a small section of the fans chanted Luis Enrique’s name, others responded with whistles.

After the game, the president visited the dressing room. He later denied that Messi had demanded Luis Enrique’s sacking, but the coach’s days are surely numbered. There were suggestions that Messi had said that if things do not change at the end of the season, he would leave. Regardless, at the end of the season there are elections and things will necessarily change, the president among them. He could hardly give guarantees beyond the summer. He can, though, act now and he may be forced to.

The candidates to replace Luis Enrique mid-season are few, with Frank Rijkaard, Jordi Roura and Óscar García among the names floated. But the situation may have become unsustainable. There will be almost 98,000 at the Camp Nou on Sunday night. As plebiscites go, it will be a powerful one and the opinion of fans seems clear. A poll in the Catalan daily Sport claimed 68% want the coach to leave. They are on Messi’s side – so must the club be. If there is an ultimatum, only one man will win it.

The game will be scrutinised like never before, examined for every clue, with every move Messi makes, or does not, taken down. It also becomes a peace-keeping mission but it will be a precarious and difficult one.

Atlético won the league there in a final day head-to-head, becoming the first team outside the big two to take the title in a decade. In doing so, they left Barcelona empty-handed for the first time in six years. Now, their conditions could not be more contrasting. There is euphoria in Madrid, paranoia in Barcelona. Victory would help Barcelona but perhaps no team has been as difficult to beat of late.

Simeone has changed everything: his team defeated Real Madrid on Wednesday, for the third game in a row. Barcelona have not beaten Atlético in seven and no one has contained Messi better. In the pre-Simeone era, the Argentinian scored 20 times against Atlético but he has now gone seven games without a goal, in which he has averaged a solitary shot every 90 minutes. Atlético’s defence will be watching his every move. And so will everyone else.