The hosts are now one point from overtaking Liverpool's league tally after a commanding performance which leaves their opponents empty handed and boss Ancelotti under pressure
A goal after 36 seconds from Javier Hernandez and a header from Nemanja Vidic were enough for the hosts, who were dominant throughout, although Frank Lampard made it a nervous ending with a goal 20 minutes from time.
For Chelsea, it was a disappointing display after battling back into the title race and the club will have to hope that both Blackburn and Blackpool can somehow beat United to prevent it from taking the Premier League crown away from Stamford Bridge.
It was another commanding display by United, with superb performances coming from all over the pitch, in contrast to the opposition which could not match its energy despite having an extra man in midfield.
Sir Alex Ferguson wrote in his program notes beforehand that Carlo Ancelotti should be kept on as Chelsea boss next season, but after this performance club owner Roman Abramovich might take a different view.
As expected, Didier Drogba was preferred to Fernando Torres at head of the Chelsea attack, with Saloman Kalou given a start on the wing as a reward for his winner against Tottenham Hotspur.
United was forced to bring in John O’Shea at left back as Patrice Evra was forced to miss out with a thigh injury and Hernandez, who scored the last time the teams met in the Champions League, was once again chosen to partner Wayne Rooney up front.
Not long ago the visitors were 15 points behind and looking like it was going to be a trophy-less season, but they came into the match with the chance to move back into first place.
Remarkably, though, the league leaders were 1-0 up after 36 seconds and it was the two players who had scored in their recent Champions League meeting who combined to give United the lead.
Park-Ji Sung moved into the Chelsea half before slipping a through ball past the outstretched foot of David Luiz into the path of Hernandez who confidently slotted it past Petr Cech to send the home fans into raptures.
Ancelotti remonstrated with Luiz straight after, but things didn’t get any better for the Brazilian defender who endured a torrid afternoon, in marked contrast to his goal in the reverse fixture.
The visitors were stunned and they had to be grateful for a flying save by Cech to his right to keep out a Rooney shot from around 30 yards which was heading straight into the corner.
It was one-way traffic and Hernandez came close to scoring again.
Ryan Giggs dribbled his way to the edge of the Chelsea box, before laying it off to Park who curled in a lovely cross which landed over Luiz and just evaded the Mexican striker who arguably should have done better.
The away side’s frustrations were encapsulated by a nasty lunge from Branislav Ivanovic which up-ended Rooney and earned him a yellow card that was not argued.
The energy of players such as Park and Rooney was giving the Chelsea players no time on the ball and the England striker came close to scoring again when he dragged his shot form the edge of the area just wide of the right-hand post.
The impressive Park was more than justifying his selection ahead of Nani on the wing and he won a corner after his swerving shot from the left was parried by Cech at his near-post.
And from the corner, the home side scored the second goal the opening quarter of the match deserved.
Giggs took it short and after stepping past Kalou he whipped in a brilliant cross which went over the head of Luiz and was headed home by Vidic.
However, the lead was nearly halved immediately, Chelsea winning its own corner which was flicked on by John Terry for Kalou to head straight at Van der Sar from a few yards out, before Ivanovic flicked the rebound into the side netting.
On the half hour mark, Kalou was tripped around 30 yards from goal and Drogba stepped up to hit the free kick over the wall and towards the bottom corner, but Van der Sar got down low to his left to parry it away.
Moments later he had another free kick from a few yards further in on the other side, but this one went comfortably wide of the goalkeeper’s right-hand post.
With five minutes left of the first half, Ivanovic once again tripped Rooney who spent a long time on the ground, but referee Howard Webb ignored the chants of the crowd and decided to keep the Serbian on the pitch.
Antonio Valencia and Rooney played a one-two which set the winger free down the right side and only a last ditch sliding tackle from John-Obi Mikel prevented Hernandez from reaching his cross in front of goal.
The visitor’s half was summed up when a clearance by Giggs was dribbled out for a United corner by Essien under pressure from the indefatigable Park.
The halftime whistle was blown soon after to loud cheers from the Old Trafford crowd.
With goals needed in the second half, Ancelotti resisted the temptation to bring on Torres or Nicolas Anelka, instead bringing on Ramires and Alex for Mikel and Luiz, whilst the hosts replaced O’Shea with Jonny Evans.
Chelsea started the second half in much brighter fashion, but it was extremely fortunate not to give away a penalty, as Valencia’s cross hit the outstretched hand of Lampard who was diving in to block it.
Moments later, Kalou went over in the United penalty area after contact by Vidic, but again nothing was given by the officials.
On the hour mark, Ancelotti threw on Torres as his last throw of the dice, replacing Kalou, but the away side’s only threat was coming from Drogba, who hit a shot narrowly wide after using his arm to control the ball.
But from nowhere the champions pulled one back, as Ramires’ deflected cross off Evans was flicked on by Ivanovic to Lampard who poked in from a few yards out.
The two goal lead was almost immediately restored, as Ashley Cole was robbed by Valencia. The ball fell to Hernandez who squared it to Rooney, but his tap-in was blocked by a diving Alex when it looked like the ball was going into the net.
Lampard’s goal left the visitors 20 minutes to try and salvage their season and although they started to play better they were thwarted by a well drilled United defense.
In a frantic last 10 minutes, both teams had chances to score, with Rooney having three in quick succession.
His first effort from the edge of the box was dragged wide, then he was through on goal but after rounding Cech his shot was saved before moments later having a shot deflected over by Alex.
Hernandez had an even better chance a few minutes later, but he headed Valencia’s drilled cross over the bar from six yards out.
Torres had been largely anonymous since coming on, but he had a chance to salvage a point for Chelsea. His shot from just inside the box was dragged wide before Hernandez reciprocated at the other end.
The home side was able to close the game out relatively comfortable and effectively seal a record breaking title.Follow Goal.com on to get the latest soccer news directly. Check out Goal.com's page; be part of the best soccer fan community in the world!