Alex Ferguson yesterday insisted it was not up to him who will be the next manager of Manchester United. The United boss had been quoted in a national newspaper yesterday as saying "when I do move on I would like to see Roy Keane taking over".

But Ferguson told the Press Association: "It's nonsense. I wouldn't presume to have the authority to make these decisions. What I said - as I have always said - is that Roy Keane has got the potential to be a manager if that is what he wanted to be.

"He is taking his badges and it all seems quite straightforward. But as usual everything has been spun out of all proportion. These were comments made eight weeks ago. He is our captain and he plays - that is his job."

The Corkman has long been viewed as management material and is currently taking his UEFA coaching badges to ensure he can get a licence when his own playing days come to an end.

However, Ferguson insists he has never actually proposed Keane as his replacement, admitting the only people qualified to make that decision are chief executive David Gill and his fellow directors.

While the idea Keane could step straight into management at a club of United's size is dubious in the extreme, it is not inconceivable he could be installed as assistant to a new manager such as Carlos Queiroz when Ferguson eventually decides to call time on his own illustrious career.

Not that the Scot is even thinking about retirement just yet.

"My passion for the job is not waning in any way," he said. "It is always a challenge at this club and it always will be. That is the great thing about it."

Ferguson also slammed the idea that Ruud van Nistelrooy could be offloaded while he remained manager. Ferguson laughed off talk that his out-of-form forward would be sold to Spain this summer.

Twelve months ago, van Nistelrooy was the subject of intense speculation linking him with a move to Real Madrid, which refused to subside even when the Dutchman personally denied he had any intention of leaving.

Now the speculation has risen once more on the back of a poor run of form which has seen the normally lethal striker score just two goals in 10 games since returning from an Achilles injury against AC Milan in February.

But Ferguson is adamant he has no intention of selling the 28-year-old, who scored 110 goals in his first three seasons at United, and remains convinced he is the equal of any striker in Europe. "The idea we could be touting the best striker in Europe for possible sale is absolute rubbish. It is not worth commenting on other than to say we have not been touting him round, we are not touting him round and there is no chance we will be touting him round in the future," added Ferguson.

Meanwhile, Fabien Barthez claims his six-month ban will not change his approach to the game. The former Manchester United goalkeeper, now with Marseille, was suspended for spitting at a referee during a friendly in Morocco. However, much of the ban, of which three months will be suspended, will be served in the close season.

Barthez will miss the last four league matches of this season, but the ban comes at a bad time for his club as Marseille are trying to hold onto the third and last qualifying position for the Champions League in France.

They go into the next round of games just one point clear of Monaco.

Barthez was charged after spitting in the direction of referee Abdelah El-Achiri during a stormy match with Wydad Casablanca in Morocco in February.