Why history is stacked against Fergie's fairytale of retaining his European crown

Win tonight, at Old Trafford against Wigan Athletic, and Manchester United will move to within two points of Liverpool, with a home game against Fulham in hand.

Next week, Derby County travel north to defend a most slender first-leg lead in the Carling Cup, and the following Saturday brings a home FA Cup fixture against Tottenham Hotspur, who have lost 12 and drawn four of the previous 16 meetings.

A first domestic treble is on for Manchester United, the quadruple too, with six matches separating them from a return to the Champions League Final, in Rome, on May 27.

And there, sadly, the fairytale may end. For if Manchester United are heading for the scrap of their lives on the home front, overtaking Liverpool and winning two cups, then adding a consecutive European triumph to it could prove mission impossible.

Indeed, a betting man with any respect for the formbook would attempt to buck the recession by placing a large wager on Inter Milan, champions of Italy, to dispatch United in the first knockout round next month.

Since 2004, the last 16 of the competition has been the graveyard of champions. Porto, Liverpool, Barcelona and AC Milan have all fallen at that stage and to escape a continuation United must defeat an Inter Milan team, marshalled by Jose Mourinho, in command of Serie A once more.

Inter were outplayed by Liverpool last season, but much has changed since then. Mourinho's gnomic expression in the Old Trafford directors' box on Sunday was interpreted as inner contempt for what had been done to his Chelsea team, but his acid observation that he saw only Manchester United on the field may, for once, be taken at face value.

No manager has greater awareness of the power of words than Mourinho and, yes, he will have calculated the double meaning and its withering appraisal of his former club, but he is at heart a pragmatist, and why should he waste a second of thought on Chelsea, when before him were his next European opponents, the global champions, due at the San Siro stadium on February 24?

He will have been generally familiar with what was on view. This is a Manchester United team that has been given the traditional shake of the reins by Sir Alex Ferguson in the second half of the season and is working its way through the field.

Ferguson plans his campaigns as expertly as a top jockey maps his route around Epsom Downs on Derby day. He stays in touch but rarely hits the front too early. Now he is beginning the kick for home.

The imaginative use of his midfield players on Sunday, Ryan Giggs and Darren Fletcher ahead of Michael Carrick, Anderson or Paul Scholes, suggests he has specific plans for each individual in the months ahead. Scholes against Inter Milan, perhaps, replicating his match-winning role against Barcelona last year.

There is no reason to be entirely pessimistic. At first glance, Manchester United, on current form, should have every chance against any opponent in Europe, but records are records for a reason, and the fact is since the European Cup changed to its Champions League format, no winner has retained the title.

Less widely realised, however, is the exhausting impact an appearance in a Champions League final has on the subsequent form of the winning club. The last champion team to make it back to the final the following year were Juventus, winners in 1996, beaten 3-1 by Borussia Dortmund in 1997. Dortmund's defence was ended by eventual winners Real Madrid at the semi-final stage, and Madrid went on to be eliminated by Dynamo Kiev in the quarter-finals the next year.

Manchester United's last attempt to win back-to-back European trophies was ended by Real Madrid, also at the quarter-final stage, at which point, adding insult to injury, the tournament became appreciably more difficult.

The 1999-2000 season was the first to contain a 32-team Champions League and the extra matches would appear to have made a tough task positively mountainous.

During the following season, Real Madrid made a good fist of the early skirmishes before being eliminated in the semi-finals by the ultimate champions Bayern Munich. Madrid exacted revenge by knocking Munich out in the quarter-finals next year, and went on to win again.

Juventus defeated Real Madrid in the semi-final the following year, and from there the dismal current run begins. AC Milan lost to Deportivo La Coruna in the quarter-finals in 2004, and subsequently no winning team has made it past the last 16. Porto (beaten by Inter Milan), Liverpool (beaten by Benfica), Barcelona (beaten by Liverpool) and AC Milan (beaten by Arsenal) all failed at that stage.

So why is this? Some cases are unique and obvious. Porto lost Mourinho and several key players after beating Monaco in the final in 2004 and were greatly reduced in quality the next year. Liverpool's victory in 2005 was borderline miraculous, the team achieving beyond the wildest imagination of even its coach, Rafael Benitez, and its malfunction next time out can hardly have been unexpected. Yet what of Barcelona, imperious in 2006, dumped by another overachieving Liverpool team 10 months later?

The standard argument concerns hunger for success. A group of players that have reached the pinnacle in Europe will be sated and will lack the drive to repeat that accomplishment the following season, is the reasoning.

Those Manchester United supporters wishing to remain upbeat will claim this as the rationale for their team not suffering the same fate as previous winners. Ferguson has a powerful ability to keep his players fresh and ambitious, usually by ditching them the moment he detects a change in attitude. There is no way United will go the way of Ronaldinho and his team-mates, the optimists will say.

Yet if it was simply a question of desire, then surely the beaten finalists would have an outstanding record the following season? After all, who could have a greater will to put things right than those that have come within touching distance and had the prize snatched away? Can anyone want a Champions League winners' medal this season more than the Chelsea captain John Terry?

It does not bear out. Valencia, beaten finalists in 2000, returned and lost again the next year, but they are the exception, and the two final defeats took so much out of them that they did not even qualify for the competition the following season.

From there it is a familiar story. Bayer Leverkusen finished bottom of their table in the second group stage in 2003, behind Barcelona, Inter Milan and (read it and weep) Newcastle United, while Juventus and Monaco fell at the second-round knockout stage to Deportivo La Coruna and PSV Eindhoven.

AC Milan were beaten by Barcelona in the semi-finals and, last year, Liverpool lost at that stage to Chelsea, but in between was another second-round exit, Arsenal, to PSV Eindhoven. So forget hunger. This runs deeper.

The players are knackered, to put it bluntly. That is what success, or a near miss, in the modern Champions League does to a team. It exhausts them. To win their second European Cup in 1977-78, Liverpool played as many matches as Manchester United must play from here to retain the trophy, and against substantially inferior opposition.

In 1976-77, the season of their first triumph, Liverpool's opponents were Crusaders of Northern Ireland, Trabzonspor of Turkey, St Etienne, Zurich and Borussia Moenchengladbach. To win the same title three decades on, Manchester United took on Roma, Sporting Lisbon, Dynamo Kiev, Lyon, Roma again, Barcelona and Chelsea.

This is not to decry Liverpool's achievement, but it is a different athletic challenge now. There is a stamina issue in European success. That is why nothing can be guaranteed the next season.

Your time will come, Sir Bobby Charlton told the abject Terry after defeat in Moscow. Really? Don't bank on it. By the time Chelsea are physically ready to take another tilt at the Champions League, who knows where the player who missed that fateful penalty will be, considering his ceaseless struggles with injury?

Even the Premier League title, which Manchester United are now favoured to win, should be approached with caution. The last team to carry their domination in Europe through to staying the distance in the domestic league the next season were AC Milan in Serie A in 2004 (although Barcelona were desperately unlucky in La Liga in 2007 when, level on points with Real Madrid and with a superior goal difference, they lost on head-to-head matches between the teams that season).

The same quartet that failed to get past the second round as European champions - Porto, Liverpool, Barcelona and AC Milan - also failed to win their leagues. Indeed, since the Champions League expanded to 32 teams, only three of eight champion clubs have won their league next year.

Manchester United are showing no sign of running out of puff just yet but the win over Chelsea merely represented the halfway stage in terms of league fixtures. The match with Wigan tonight is the turn for home, but from there circumstances dictate the run gets tougher by the stride, even if the fixture planners have been generous to United, with so many crucial matches at home.

United have certain other advantages - the absence of England at the European Championship has left key players such as Wayne Rooney fresher than some opponents - but Ferguson, a regular at the blue riband events from Cheltenham to Royal Ascot, will be aware that the final straight of any race worth winning is rarely downhill.

The manager will also be a devotee of form and will understand that, as European champions, his team are no longer favoured by course and distance, no matter its experience of the terrain. To achieve on all fronts this season - and one above all - United must not just make history. They must defy it.