Although United are used to opposition supporters baiting them on their travels, the atmosphere when they visit West Ham ranks alongside Anfield and Elland Road for intimidation.

Sir Alex Ferguson is at a loss to explain it, so the answer is far too deep-rooted and historic for Fletcher to know.

But while the Scotland star lacks the longevity to find that solution, he has enough experience of life at Old Trafford to know the bile will only galvanise United as they look to take a stranglehold on another Premier League title.

"We are the Premier League champions, European champions and world champions. West Ham want to turn us over and their fans will be right up for it," said Fletcher.

"The atmosphere down there is hostile. Sometimes you watch a game on TV and it seems fine but for us it is different somehow.

"When you are successful people try to knock you down. Long may it continue is all I can say."

Eye-contact is inadvisable. But when it does happen, Fletcher knows exactly how United intend to respond.

He continued: "You must meet the challenge head on. If you go to take a corner and you are getting stick you just have to laugh it off and respond in the best way possible by winning the match.

"You need to channel it into a determination to prove them wrong. That is what we tend to do."

United have tended not to do it that successfully in the past couple of years.

They have lost on three of their last four meetings with the Hammers and last season's trip to east London is part of a sequence of results in the capital which belies United's status as undisputed number one.

However, at a time of year when points gathered provide the platform from which a successful championship campaign can be constructed, West Ham are being viewed by some as one of the last remaining hopes of United getting toppled this term.

Although the Red Devils still have to tackle Liverpool, Aston Villa, Manchester City and Arsenal, all those games are at Old Trafford.

Take West Ham out of the list and United's run of away games is not too arduous, suggesting points need to be dropped at Upton Park if the title race is not going to become a one-horse stroll to the line.

"We have got ourselves into a great position," said Fletcher.

"It has come as a surprise how quickly we have managed to get ourselves in front but it is in our hands now, that is all we can ask.

"We know if we win our games we will win the league."

No-one is expecting United to win all their games but that Fletcher is now declaring the time has arrived for the Red Devils to 'kick on' must be a worry for Liverpool, Chelsea, Villa or anyone else thinking they have a chance of lifting the trophy themselves.

For once, the basis of United's title drive has come from the back, with a run of 12 successive clean sheets that has allowed Edwin van der Sar to enjoy glory that matched his Champions League-winning save in Moscow last term.

"Fair play to Edwin," said Fletcher. "After saving the penalty in the Champions League Final last season he has come back even stronger this year.

"Ronaldo has made a few people laugh this week by trying to take some of the credit, saying it is a team effort. But Edwin and the defence deserve most of the plaudits."

As key figure in United's engine room, Fletcher realises he will not improve so late in his career.

However, the Dalkeith-born midfielder recognises that, at 38, Van der Sar is using his vast experience to maximum effect.

"Goalkeepers do get better in their late 30s," he said.

"It is not as if your legs can go, so the most important thing is experience and knowing what to do at the right time.

"Goalkeepers cannot afford to make mistakes because they cost matches.

"But with Edwin the decision-making seems to be instinctive now."