Manchester Utd v Millwall: Millwall have travelled to Cardiff on the back roads. They are the first side in 51 years to sneak through to the FA Cup final without meeting a team from the top division. Today the tournament gets its own back by putting them in the path of a juggernaut.

The television commentators will not run short of picturesque incongruities when, for instance, Marvin Elliott, who was an apprentice at The Den a year ago, has to tackle Ryan Giggs, appearing in his fifth final.

There is, however, an even odder disparity. Manchester United may be accustomed to gathering silverware, but this season's FA Cup is still far more significant to them than it is to their opponents.

Nothing will prevent Millwall, who have had just one win in eight matches to end a slovenly 10th in the first division, from revelling in the mini-miracle of their presence at the Millennium Stadium. No matter what becomes of them this afternoon, they will still celebrate qualification for European football for the first time in their history.

United are so very much harder to please and, in some quarters, victory has been disregarded before it has even had a chance to take place. Roy Keane said a while ago that the FA Cup final could be no more than a good day out. He was not, of course, contemplating defeat and United's vital purpose against Millwall is to eradicate any chance of a fiasco.

Failure is virtually inconceivable since the opposition do not have the calibre of player deployed by, say, underdogs like the 1973 Sunderland, with Dennis Tueart, or West Ham, who had Trevor Brooking to head a winner over Arsenal in 1980.

The Millwall player-manager Dennis Wise will be around in one capacity or another, having returned from a trip to the Italian specialist who got him fit for Chelsea's 1998 Cup Winners Cup final. The healer was now ministering to a 37-year-old's leg injury and while Wise is expected to be on the pitch one wonders how the midfielder will last the pace.

Alex Ferguson will be anxious to put down a marker, just as he did in 1990. The FA Cup then became the first trophy of his time at Old Trafford. He had been at work for four years and, without that breakthrough, Ferguson's sacking might have been unavoidable.

Soccer is repetitive and, just as it was 14 years ago, an FA Cup final can be Ferguson's means of showing that a potent team is under construction.

With Keane fit again following his hamstring problem, someone must make way in the midfield. If Ferguson wants to show that a new line-up really is being assembled, he might have to relegate Phil Neville.

Logic steers Ferguson in that direction after the large claims he made on behalf of Darren Fletcher when he identified the 20-year-old's potential to become one of the great players in the club's history.

There is a practical need to encourage the Scot. Ferguson now accepts that the policy of using Keane intermittently has failed. The captain cannot be an occasional performer. Ferguson has come round to the view that he must pick him far more often despite the after-effects of the hip operation on the player.

Should Keane be unable to cope with the schedule, though, the manager will have to establish a credible midfield that does not include him at all. He therefore has to satisfy himself that Fletcher is ready to come to the fore. The youngster's effect on the FA Cup semi-final success over Arsenal has encouraged Ferguson's faith that he is ready.

If all goes well for United, today's match will serve as a kind of lap of honour for that win at Villa Park. The contest with Arsene Wenger's team was often abrasive, but the result soothed the fans in a year of discomforts.

They detected confirmation there that Ronaldo is not just a flibbertigibbet whose dragback is more of a mannerism than a threat. In his first season with the club, the winger has started to look like a match winner.

Ferguson aims to send out a balanced team that can see off Millwall with thoroughness and panache. The manager will hope to present the crowd with his draft of the future. The aim is to end one season by making United fans look forward to the next.