The Red Devils have rejected speculation that Mourinho is at the top of their managerial hit-list - and is the choice of Ferguson to join the club.

However, with Ferguson due to celebrate his 67th birthday on New Year's Eve, the timing of his exit and Mourinho fulfilling a three-year contract at Inter Milan could coincide.

Ferguson has always been coy about discussing his retirement plans.

However, he did reveal in the summer he probably not go on beyond 2010. Now, in an interview paying tribute to Sir Bobby Robson, who was sacked by Newcastle when he was 71, Ferguson claims he will not still be in a job when he reaches 70.

"I won't be doing a Bobby Robson and be a manager when I am 70," he told the Mail on Sunday.

"It is just knowing when to quit.

"Football is like a drug which is difficult to give up.

"My appetite and enthusiasm are as strong as ever. I love watching Manchester United. We have some terrific players who are only going to get better."

Appointing Mourinho would ease any fears among fans that Ferguson's successor could not hope to reach the standards set by the Scot.

At Chelsea, Mourinho proved he had a big enough ego to handle any situation, even if Roman Abramovich ultimately grew impatient for Champions League success, which continued to elude the Portuguese coach.

However, as Mourinho did win the competition - and the UEFA Cup - beating United on their way to victory over Monaco in 2004, his credentials are virtually impeccable.

Only a reputation for pragmatic rather than flamboyant football goes against him.

Not that United are claiming there has been any contact, or even discussion of Mourinho within Old Trafford walls.

"As we have said many times before, there has been no discussion about who will eventually succeed Sir Alex," said a United spokesman.