Twenty years ago a Copa Libertadores-winning legend turned up to manage mid-table fourth tier side Oxford United.

Six months later Ramon Diaz and the rest of his seven-man entourage were blocked from even entering the ground.

It seems unlikely anybody will ever join the former River Plate manager, who played for Argentina, Inter Milan, Monaco and others, in winning South America’s top tournament – and the League Two manager of the month award.

BBC Sport tell the story with help from former players Steve Basham, Chris Tardif and Lucas Cominelli, BBC Oxford editor Jerome Sale, and Jean Marc Goiran, the man who brokered the deal and acted as assistant manager, translator and unofficial chief executive.

‘Who are these guys?’ – How it started

Oxford United, the 1986 League Cup winners, were in a slump, having dropped from the second tier to the fourth since 1999 – and were sliding down League Two when owner Firoz Kassam sacked Graham Rix.

Kassam, the club’s unpopular owner, invited out-of-work manager Chris Turner to watch their 1-0 defeat by Swansea – and most people thought he was the new manager, including the Oxford Mail, external and some players.

But instead… “It was quite bizarre,” said former U’s striker Basham. “Five or six guys came in, in a line. They all stood in front of us and none of them spoke a word of English, apart from one translator.”

Goiran said “all the players had wide-open eyes wondering ‘who are these guys?'”.

Those guys were Diaz, head coach Horacio Rodriguez, another coach Raul Marcovich, Goiran, fitness trainer Pablo Fernandez, doctor Rafael Giulietti and translator Giuilliano Iacoppi.

But wait, how did it come to this? It all starts in Monaco – where Kassam and Goiran lived and Diaz also had a home having played for the club.

Kassam approached a friend of a friend, Goiran, who has worked as a football agent and consultant, to help him find a manager and the Monegasque suggested Diaz – who had left River Plate in 2002.

At the time it was widely reported that Diaz was not being paid to be Oxford manager – and Kassam said he had “promised him shares in the club in return for success”.

But Goiran, speaking 20 years on, says Kassam’s company Firoka, but not the club, instead paid Diaz and Goiran consulting fees in Monaco.

And the question many have asked – why did a manager with five Argentine titles and the Copa Libertadores come to League Two Oxford?

Goiran says it was part of a project to get to the Premier League in five years – but after a bitter ending, Diaz, who is now Corinthians manager in Brazil, never worked in England or even Europe again.

“When they first came in, there were grand talks about redeveloping the stadium, putting a new stand behind the goal and taking us into the Premier League,” said goalkeeper Tardif.

‘Very new and fresh’ – How did training change?

Back in 2004 there was less foreign involvement in the lower leagues in England, so it was an even big culture shock then than it is now.

But many of the players bought into the new training ideas, although some struggled to adapt.

“They brought something very new and very fresh to Oxford United at that time,” said Basham, who played for the club between 2002 and 2007.

“It was way before its time. They came in with ideas and the philosophy that probably hit the English game two, three, four years later, certainly in the lower leagues.”

Rodriguez would be hands-on – with Diaz overseeing things. To some around the club Rodriguez was seen as the traditional boss of the team with Diaz almost a director of football.

Diaz and his coaches only spoke broken English, so had to communicate via their translator.

But Goiran, who was involved on the training pitch too, says Diaz was the manager and had the final say in everything.

Basham said: “He [Diaz] would come in amongst the team as we were laid out in our shape and he would take us through with movements. Very different, but it worked.

“He’d physically move you, he would then have you alongside him and he’d make the runs and you would make those runs with him.”

Goiran said: “It was a very nice atmosphere. It was a great adventure. We changed the way they trained, the mentality. We taught them they are football players.”

They were popular figures off the pitch too.

BBC Oxford’s Sale said: “Ramon and his staff were imposing and impressive, but also gentle and friendly.

“He once asked me for $100,000 for interviews. I said the BBC wouldn’t stretch that far. He said just to bring him a decent coffee next time then.”

‘More of a Pep philosophy’ – Dream start on the pitch