United need just one more point to seal the title after they claimed a 2-1 win over Chelsea in their huge showdown at Old Trafford.
Javier Hernandez took just 36 seconds to break the deadlock as he seized on a David Luiz error to net his 20th goal of the season.
Skipper Nemanja Vidic headed home a Ryan Giggs cross in the 23rd minute as United deservedly doubled their advantage although Didier Drogba and Salomon Kalou both went close for the visitors before half-time.
Chelsea threatened an unlikely comeback after Frank Lampard's 68th-minute header restored hope but a relieved Sir Alex Ferguson saw his side cling on for a priceless triumph.
The defending champions needed a win to leapfrog United on goal difference but Carlo Ancelotti's men are now six points behind with just two matches remaining.
Full Match Report
Manchester United celebrated like champions at Old Trafford after a 36-second opener from Javier Hernandez and a Nemanja Vidic header took them to the brink of the Barclays Premier League title.
One point from the final two matches against relegation-threatened Blackburn Rovers next Saturday and Blackpool on the final day of the season will be enough to seal a championship which will take them past the mark Liverpool have been on for so long.
Sir Alex Ferguson felt victory over closest rivals Chelsea was worthy of a couple of bows to the Stretford End as he knows, as do all United's rivals, the prospect of them not getting over the line now is unthinkable.
Built up as the title decider for a week, so important Ferguson selected a shadow side for a Champions League semi-final, these matches are so often a disappointment.
Not this one. Not when United were ahead so quickly.
Carlo Ancelotti must have been devastated to concede quite so simply so early in the match.
Ryan Giggs began the move, stroking a short pass forward for Park Ji-sung, who turned out to be one of United's most effective players.
The South Korean knew Hernandez would be right on the shoulder of the last defender. He could not legislate for that defender failing to cut out the pass.
POWERED HOME
Ancelotti made his feelings known about that in the aftermath as he berated David Luiz from the touchline. Hernandez was not hanging about to consider it, darting forward before burying his 20th goal of the season into the bottom corner.
Old Trafford erupted and then watched spellbound as their team produced an awesome display of attacking power.
Wayne Rooney was agonisingly close on two occasions, Hernandez should have tucked home Park's far-post cross despite Luiz's touch. Park himself brought an excellent save from Petr Cech.
From the latter effort United gained the corner that brought their second as first Salomon Kalou, then Branislav Ivanovic was slow off the mark.
Kalou's crime was to allow Park to race past him and play a short corner with Giggs.
The Ivorian was then beaten too easily as Giggs nipped to the byline before dropping a cross into the heart of Chelsea's box where Vidic strode past fellow Serb Ivanovic and powered home from close range.
Chelsea did create opportunities themselves. Edwin van der Sar made an excellent save to repel Kalou and Didier Drogba went close on a couple of occasions.
But those chances came against the backdrop of a game set up exactly as the Red Devils would wish, which made the otherwise outstanding Rooney's decision to react to the baiting he was receiving from the visiting fans all the more puzzling.
Having expressed his concern about United being on the wrong end of a refereeing decision, Ferguson could at least console himself his side had established a winning position before Howard Webb turned down their penalty appeals for what seemed a clear Frank Lampard handball to block Antonio Valencia's cross.
BETTER OPPORTUNITY
With no comeback in sight, Fernando Torres became the third Chelsea replacement after an hour.
The change brought the reaction Ancelotti was looking for though as Ivanovic climbed highest to reach a Ramires cross and headed down for Lampard, who prodded home from close range.
United should have snuffed the visitors' lingering hopes out immediately though as Hernandez nicked possession away from Ramires and seemed to have presented Rooney with a tap-in, only for Alex to slide across to make a crucial goal-line clearance.
Rooney then spurned three chances to seal the contest, firing the first wide, inexplicably failing to even shoot with the second, before finally having an effort deflected over by Alex.
Hernandez missed an even better opportunity when he nodded Valencia's teasing cross over from six yards.
It was all happening at the wrong end for Chelsea though, apart from a Torres effort that never threatened.
Indeed, the visitors were resigned to their fate long before the final whistle, with United knowing they could be celebrating history at Ewood Park next Saturday just as Manchester City are taking the field for their first FA Cup final in 30 years.
