That leaves Sir Alex Ferguson's side with a seemingly unassailable lead in the Premier League, in the last 16 of the Champions League and the quarter finals of the FA Cup as they seek an unprecedented clean sweep of trophies this season.
But while the Manchester United manager has insisted "a deflected goal off someone's backside" could cost them the quintuple, they are inching ever closer to one of the most remarkable feats ever achieved in club football.
Premier League - chances of success: 4.5/5 Seven points clear and with a game in hand at home to Portsmouth, the title is now Manchester United's to lose. It is a measure of how much better the Old Trafford side are than all of their domestic rivals that they have managed to set a blistering pace while rarely hitting the heights of last season.
They have scored three goals or more in the league on just six occasions, compared with eight at this stage last season. That difference may not seem significant, but both the quality of the opposition and the locations have changed. Last season, United beat Sunderland and Aston Villa 4-0 away from home. They have only hammered one side, West Bromwich, when not in familiar surrounds this season.
But not one of their rivals have managed to take advantage of Ferguson's men not being at their best. Arsenal cannot win at home. Chelsea have sacked their manager. Aston Villa, always unlikely challengers, are slowly fading. Most disappointingly for neutrals, Liverpool have wasted their strong start. Rafa Benitez's side have imploded since January, and turned a race into a procession.
There is little hope of a United wobble to make the Premier League interesting again. Liverpool, Villa and Arsenal all visit Old Trafford, but all three would have to win to turn the tide against United's 11th Premier League title and 18th league championship.
Trips to Wigan and Sunderland will not be easy, and the Manchester derby will no doubt be tough, but for United to fail they would, essentially, need to lose four games. For a side unbeaten since November, that is not going to happen.
Champions League - chances of success: 3/5 Sir Alex Ferguson knows retaining the Champions League is now the biggest obstacle to landing five trophies this campaign. Their last 16 tie with Inter Milan is delicately poised after a goalless away leg, and while that should make United favourites to progress, an Inter goal at Old Trafford would be disastrous.
Of 21 teams in the competition's history who have drawn their away leg 0-0, only six have gone out, although United have, on two occasions, been the victims. No side, though, has ever retained the trophy since the European Cup became the Champions League, and that is why it is on the European stage where Ferguson is right to preach caution.
Should United beat Inter, they will be just two ties away from the final in Rome, but the calibre of opposition is such that it is premature to suggest United all but have the competition in the bag. The dangers posed by their Premier League rivals, all well placed to progress, are well-documented, while Bayern Munich, United's old foes, are struggling domestically but imperious abroad.
The main threat, though, comes from Barcelona. Pep Guardiola's side are enduring something of a blip at present, losing two in a row in the league and only drawing with Lyon, but they remain the finest attacking side in Europe. Assuming Guardiola can arrest the slide, at some point United will probably have to beat Barca if they are to enjoy more European glory.
FA Cup - chances of success: 4/5 It was to the vaguaries of the FA Cup that Ferguson pointed when he wanted to illustrate how unlikely a quintuple is. One deflection at Fulham, he suggested, could undo it all.
Ferguson should know. With Liverpool and Arsenal already out last season – and Chelsea soon to follow – Manchester United were clear favourites at the quarter final stage.