It happened in 2011, before the first leg of the Champions League semi-final between Real Madrid and Barcelona. Reeling from defeat to Madrid in the Copa del Rey final to Madrid, Camp Nou coach Pep Guardiola abandoned the Barça party line to round on Real. At the Santiago Bernabéu, Guardiola gave an astonishing press conference that saw him offer up a salvo of unforgettable quotes about referees, Madrid boss José Mourinho ("es el puto amo" ["he's the fucking master"]) and the supposed coercion of reporters by Real president Florentino Pérez. Barcelona won 2-0 and many pundits highlighted the positive effect of Guardiola's outburst on his team's morale (Pep's players welcomed him back to the team hotel with a round of applause).
On Monday, stand-in coach Jordi Roura followed Guardiola in straying from the Barcelona narrative to put pressure on Alberto Undiano Mallenco, the referee appointed to take charge of the arch rivals' Copa del Rey semi-final second leg. If he seemed to be parroting a line fed to him (probably by Skype) it's because he was. If it did not cause the same shockwaves as two years ago, it is because he lacks Pep's charisma and clout - not to mention the Barcelona legend's look of the tortured beau.
Reading between the lines, it seems that Barça - like two years ago - are using agitation to breathe life back into their team, to dispel crisis and to create a diversion. The feeling is that the team management are afraid. Afraid enough to concede a large chunk of the moral high ground they have cultivated and held over Madrid. Unable to change their 'tiki-taka' style of play, their only option is to serve up verbal volleys, painting themselves as the victims. It is a tactic that Mourinho has made his trademark.
The Real coach could not resist the temptation to hit back at Roura's words, lacing his retort with irony; meanwhile, no news has reached us of an ovation for the Barcelona coach at his team hotel. Undiano is unlikely to be affected, either; chiefly because the strength of the message mirrors the strength of the messenger. And Roura is no heavy-weight.
All that one can be sure of is that the first-leg draw at the Bernabéu leaves the tie finely balanced. It seems almost a certainty that Madrid will score at the Camp Nou, an expectation underlined by Barcelona's recent defensive frailties: they have now conceded in 11 consecutive games (1.45 goals per game). With this in mind, the hosts' fear is justified, and their panic is excusable.
Most striking about the sides' respective line-ups is that Lionel Messi and Cristiano Ronaldo both play with as little as ever to choose between them. The Argentine appears down in the dumps, although this does not stop him filling his boots with goals. He is so important to his team that he is now running the risk of being too important. No-one is in any doubt that the lack of alternatives in Barcelona's play is directly down to him: first he didn't like tall forwards, now he doesn't like any forwards at all. His obsession with controlling everything his team does is forcing him to drop into midfield to give the pass which only he could be on the other end of.
However, Cristiano is heading in the other direction. He has shaken off his narcissism to revel in team-play. The Portuguese star no longer trails in Messi's wake; watching these two titans clash is one of the most appetising elements of the evening of football awaiting us.
If Barcelona accept that they need two or more goals to progress, the inclusion of David Villa appears to be a must. If Mourinho possesses any sensitivity to justice, Kaká will play. If the Real supremo is bold, his line-up will include a traditional centre-forward (probably Gonzalo Higuaín). A further sub-plot will be that of Andrés Iniesta versus Mesut Özil.