Pep Guardiola has tried to stick to German in all his public appearances since becoming the coach of FC Bayern. As he fumbles charmingly for the right word, he comes across as respectful, diligent, eager to learn. Last Thursday he reverted to Catalan for five minutes and reminded everyone that behind the humble demeanour is a guy who won't tolerate being messed about.

Last week, Santos vice-president Odilio Rodrigues was quoted by Brazilian media saying Guardiola tried to hijack the transfer of Neymar to Barcelona, hoping to persuade the player to join Bayern instead.

Rodrigues said Guardiola hinted to Neymar's camp that Barcelona's coach Tito Vilanova could struggle to find a role for Neymar in a team that has been set up to serve Lionel Messi.

Guardiola therefore stood accused of trying to sabotage the interests of his former club, and worse, casting aspersions on the abilities of his friend and former assistant, whose work at Barcelona has been interrupted by bouts of treatment for cancer of the parotid gland.

At Thursday’s press conference at Bayern’s pre-season training camp, Guardiola was asked for his reaction. His reply was cold and furious and clocked in at over 1,000 words – longer than the article you are now reading. Guardiola spoke in paragraphs and it was plain these issues had simmered in his mind for some time.

He admitted having met with Neymar’s father, but denied trying to persuade him to join Bayern. He reserved special contempt for the suggestion he had behaved with anything other than total respect towards Vilanova.

Although Guardiola never spoke his name, everyone understood his anger was directed at Barcelona president Sandro Rosell.

Revolution
This summer marks 10 years since Rosell arrived at Barcelona as part of the executive team led by the newly-elected president Joan Laporta. It was a revolution self-consciously modelled on John F Kennedy's Camelot.

Laporta was the sunshine boy, but he would govern in consultation with a committee of the best and the brightest, and Rosell would be the biggest brain in the brains trust. Together they would drag Barcelona into the 21st century.

It’s easy to forget how much dragging had to be done. In the summer of 2003 Barcelona had slipped out of the list of Europe’s ten richest clubs – according to Deloitte, that year Barcelona had a smaller turnover than Newcastle United – and they had won no trophies for four years.

Rosell made an important contribution at the beginning. In his former job with Nike, he built a network of contacts in Brazilian football that helped Barcelona beat Manchester United to the signing of Ronaldinho, who would become the best player in the world.

Rosell and Laporta soon disagreed over the position of the coach Frank Rijkaard, who endured a difficult first six months. Laporta backed Rijkaard, while Rosell wanted to hire Luiz Felipe Scolari.

Laporta’s patience was rewarded as Rijkaard turned the team around and led them to a series of brilliant successes.

As Laporta basked, Rosell brooded: the president’s leadership style was less consultative and more dictatorial than he had bargained for. In June 2005 Rosell resigned, criticising Laporta in an open letter that contained the withering observation that a Barcelona president “should work with discretion, honesty, efficacy, humility and transparency”.

In June 2010 Laporta’s second presidential term expired and Rosell won the election to succeed him. Now he would have the chance to show how a proper Barcelona president acted.

Laporta had honoured Johan Cruyff with the title of honorary president. Rosell stripped Cruyff of the title, claiming it had been unconstitutional to give it to him in the first place.

More credit
Perhaps it sticks in Rosell's craw that Cruyff, who has had no official role at Barcelona since quitting as manager in 1996, has received more credit for their last decade of success than Rosell himself, who has been involved in running the club for much of that time.

As Cruyff said in 2011: “If you pick up any newspaper in the world and there is an article talking about the great style of Barça, my name always appears and makes me even more famous.”

Despite his skill in whipping the balance sheet into line, nobody talks about the mastermind Sandro Rosell.

Last month, Cruyff criticised the Rosell-driven decision to sign Neymar, saying the transfer risked disrupting the squad and that Barcelona should now prepare for the possibility of selling Lionel Messi.

The fact Cruyff’s comment was probably motivated by a desire to annoy Rosell doesn’t mean he didn’t have a point.

Messi’s form has been so exceptional mere brilliance might now seem rather disappointing. If he finishes next season with 30 goals, what would be a fantastic season for any other player will look like a dramatic decline in effectiveness for Messi.

Then it is easy to imagine questions arising over whether Rosell’s club is still the best place for him to be. And the rise of Bayern means that for the first time, there would be an obvious alternative club for Messi, a team where he could play with team-mates even stronger than he has at Barcelona, under a coach who knows his game better than anybody.

And by the sounds of it, Guardiola is not prepared to cut his old club any slack.