In his press conference ahead of the first leg of the Champions League semi-final between the two great Spanish rivals, Guardiola abandoned his usual facade of indifference towards Mourinho in spectacular fashion.
His motivation was Mourinho's accusation that Guardiola had complained about referees who got their decisions right following Madrid's narrow victory in the Copa del Rey final, an accusation that drew a fiery response from the Barcelona boss.
Guardiola said on Tuesday evening: "Tomorrow at 8.45, we will meet each other on the pitch. Off the pitch he has already won. In this room [press room], he's the f*****g chief, the f*****g man, the person who knows everything about the world and I don't want to compete with him at all. It's a type of game I'm not going to play because I don't know how.
"I won't justify my words. I congratulated Madrid for the cup that they won deservedly on the pitch and against a team that I represent and of which I feel very proud. Off the pitch, he has already won, as he has done all year. On the pitch, we'll see what happens."
Whether Guardiola's response will ultimately be seen as evidence of mental disintegration or a stroke of genius to inspire his players, who drew 1-1 in the league match between the two clubs recently before losing the cup final, Barcelona have stood shoulder to shoulder with their coach.
Bartomeu has praised Guardiola for his conduct across the course of the campaign and said that it was only to be expected that he would eventually respond to such provocation from Mourinho.
"Pep has had exemplary behaviour throughout the season and now has had to respond," Bartomeu said. "Enough is enough.
"There has been [an] answer now, because they have not stopped all year while we have devoted [ourselves] only to soccer. Our coach, we would say [is] devoted only to compete, the sport, football and winning games."