This morning they stand 11 points clear and, though Arsenal can close the gap to three if they win their games in hand, a third successive title appears well within United's grasp. This position is due, though, not so much to United's excellence as to the failings of their rivals.
In the intervening months United have taken 22 points from 11 games, one more than in the 11 matches during the Champions' League. Yet their lead has been extended by six points. We are now in the unusual position of looking enviously at the exciting finish in prospect in Scotland.
Even more chilling for the rest of the Premiership is that they have achieved this despite often fielding weakened teams. While this has not been as deliberate as in the FA Cup, enough first-choice players have been "rested" to suggest United believe they are now so superior even their reserves are ahead of the rest.
Though United play the game the right way and are predominantly English in construction (eight of Saturday's starters, against three of Chelsea's) this is not good for the long-term health of the game. Both Dennis Wise and Alex Ferguson said United's competition was stronger than in recent years but, as their Champions' League results showed, so are United.
On the plus side the game in general is better, long-time observers may wince at the frequency of basic errors in the Premiership but the speed of the game must be taken into account when comparing skill levels. Even in the last decade the game is immeasurably faster, it does not always make for better football but most modern teams would overwhelm their forbears. United's concentration on youth has also set a benchmark. Clubs may be looking overseas for players more than ever but this is in the short-term. In the long run many are seeking to emulate United.
On Saturday Ferguson paid Chelsea the compliment of fielding his best available XI (as he does against all main rivals). He was still without Ryan Giggs, who was badly missed (and, of course, Roy Keane) but United were comfortable if uninspiring winners. While they are still searching for the panache of autumn there was a solidity about their play which augured well for Wednesday's European Cup quarter-final in Monaco.
United defended with a resolution typified by Ronnie Johnsen's refusal to be intimidated by Mark Hughes. The one caveat was Gary Pallister's departure with another back complaint but at least Henning Berg had an hour to settle and, by the end, was as commanding as his fellow Norwegian.
The midfield, with Nicky Butt, unusually, on the left, was tenacious in the tackle and supportive in attack. Paul Scholes was magnificent, what a wonderful and versatile player he has become. Chelsea, despite Wise's pugnacity - he stamped on red stockings as if they were poisonous spiders - were swamped in this area.
The three-forward system may have worked against Arsenal, when its width blocked their avenues of attack, but it has failed against Leicester City and Manchester United. It leaves the midfield undermanned and Gianfranco Zola, without a goal since November, looks lost on the left. Gianluca Vialli, having given his first XI a chance to repay his faith, may have to take a hard decision for Thursday's Cup-Winners' Cup tie against Real Betis.
One fears for Chelsea in Seville but United look worth a bet in Monte Carlo. Monaco's pace may be a problem but first the likes of Thierry Henry must be given the ball. United always look capable of scoring and would be happy with a 1-1 draw. Giggs, however, will be missed, and not just for his attacking brio. There were times when his team-mates looked to play the ball left only to realise their outlet was absent.
There was width in the goal, an eight-man nine-pass move which began with Peter Schmeichel rolling the ball out on the right, switched to Denis Irwin on the left, and ended, after a neat one-two between Teddy Sheringham and Andy Cole, with Phil Neville shooting in off the far post. It was an exceptional finish for a player who had never scored a senior goal before.
The fluency of this move was rare in a game Ferguson admitted was "scrappy". Both teams began with a hesitancy that betrayed their recent search for form but United always had a better balance, never looked like conceding, and might have scored through Cole, Sheringham and Butt.
With both Chelsea and Liverpool having taken three points from 15 their challengers are fading. Vialli refused to surrender but a United victory over Arsenal at Old Trafford in a fortnight, another morning kick-off, will effectively ensure Ferguson becomes the first manager to lift three successive championships. An impressive reward but his eyes are on back on Europe, starting this Wednesday.
Goal: P Neville (32) 0-1.
Chelsea (4-3-3): Kharin; Clarke, Duberry, Lebouef, Le Saux, Petrescu, Wise, Di Matteo; Vialli (Flo, 78), M Hughes, Zola. Substitutes not used: Lambourde, Nicholls, Newton, Hitchcock (gk).
Manchester United (4-4-2): Schmeichel; G Neville, Johnsen, Pallister (Berg, 27), Irwin; Beckham, P Neville, Scholes, Butt; Cole, Sheringham. Substitutes not used: McClair, Solskjaer, Thornley, van der Gouw (gk).
Referee: S Dunn (Bristol).
Bookings: Chelsea: Wise, Zola, Lebouef. United: Butt, Sheringham, Cole.
Man of the match: Scholes.