Liverpool had temporarily taken over top-spot, after their 2-1 win at Middlesbrough earlier in Saturday, but United reclaimed first place with all three points at West Ham.
United comfortably took all the points in East London, but The Hammers did look as if they might spring an upset in the first half.
West Ham took the lead when Steve Lomas converted Vladimir Labant's cross after eight minutes - his first goal in 18 months.
David Beckham (pictured) then scored a great goal nine minutes later to level. The England skipper picked up the ball on the edge of the area and he chipped the ball over the stranded David James to grab his 13th of the season.
The Hammers came back again and with two minutes had retaken the lead. Frederic Kanoute grabbed the goal when he met Sebastien Schemmel's cross with great aplomb.
West Ham had only conceded seven home goals before this game and would have thought they could hold on, but again United came back strong and Beckham was again at the heart of the move that led to the champions' second.
Christian Dailly brought down Ruud van Nistelrooy, which gave Beckham the chance to whip in one of his trademark free-kick's which was met by Nicky Butt who headed powerfully past James for his first goal in a year.
Into the second half United then upped their game and within ten minutes had taken the lead. Ole Gunnar Solskjaer created the chance as he turned Nigel Winterburn and Tomas Repka before turning the ball back for Paul Scholes who made no mistake from close range.
Solskjaer then added the fourth himself just after the hour mark when he pounced on a rebound van Nistelrooy effort to finish past James.
Just when the game looked to be over with United cruising, but West Ham struck again.
The ever-dangerous Kanoute created the chance down the right and he crossed for Jermain Defoe who pounced to give The Hammers hope.
However, United sealed victory in the last minute when Beckham blasted home from the penalty spot after Repka has brought down Scholes.
Newcastle captain Alan Shearer missed a last minute penalty at St James Park, which meant the home side could only muster a 2-2 draw with lowly Ipswich Town.
George Burley's side actually took the lead twice, only for The Magpies to peg them back twice.
After a goalless first half the game came to life just four minutes into the second period when Marcus Bent was sent clear by strike-partner Marcus Stewart and he despatched the ball through Shay Given's leg to make it 1-0.
Newcastle's French winger Laurent Robert then produced a moment of magic to bring the sides level. Nolberto Solano was brought down 20-yards out and Robert curled home the resulting free-kick to leave Matteo Sereni with no chance.
It then seemed like the home side would go on and seal victory, but again Town came back and took a shock lead.
A long-ball down the middle saw Nikos Dabizas inexplicably miss the ball and his defence partner Andy O'Brien could only divert the ball into Bent's path who again made no mistake and finished well.
Newcastle then again came strong and with just four minutes left Shearer headed home a Robert cross from point-blank range.
The Toon faithful then thought they had grabbed a shock and what would have been an undeserved win when Chris Makin dived in and brought down Clarence Acuna to conceded a penalty. But Shearer blasted the ball past the post to make sure the game finished level.
Chelsea took advantage of Newcastle's slip up and are now just three points of the fourth placed North East club, after they thumped Sunderland 4-0 at Stamford Bridge.
French defender William Gallas opened the scoring after 24 minutes with his second in just three games. Marcel Desailly headed Graeme Le Saux's corner into Gallas' path to give him a simple task of prodding the ball into the net.
Sunderland put up some stern resistance, but The Black Cats were without Kevin Phillips and Claudio Reyna which left them with little options going forward.
Chelsea did not make it two until 14 minutes from time when Jesper Gronkjaer exchanged passes with Jimmy Floyd Hasselbaink before playing the ball into Eidur Gudjohnsen, who first touch took it past the Sunderland defence from where he dinked the ball over Thomas Sorensen.
Mikael Forssell then added to his growing and scored once again after coming on as sub. He played a one-two with Le Saux before hammering the ball into the net from 18 yards.
Chelsea's Italian midfielder Sam Dalla Bona then completed the scoring with a great finish from the edge of the area.
At the other end of the table Everton gave David Moyes the perfect start to life in the Premiership with a hard fought 2-1 win over Fulham at Goodison Park.
Just 20 seconds into the game The Toffees were in front, after David Unsworth latched onto Tomasz Radzinski's knock-down to volley the ball past Edwin van der Saar.
Van der Saar was then culpable himself when his fluffed Andy Melville's pass back which allowed Everton skipper Duncan Ferguson to fire home the simplest of goals.
However, just when Everton looked to be settling down after their fantastic start - Danish midfielder Thomas Gravesen was sent off for two bookable offences, although it would seem that Fulham forward Louis Saha made the most of the second challenge.
Fulham came back into the game just a few minutes into the second period when Barry Hayles broke into the area and crossed for Steed Malbranque who was left with the simple task of finishing from close range.
But, Everton defended wonderfully and despite riding their luck they managed to hang on for three priceless points. It is now five straight defeats for Jean Tigana's side.
The game between second bottom and third bottom at The Reebok Stadium, ended in a crucial 3-1 win for Derby over Bolton.
Malcolm Christie opened the scoring after 22 minutes when he capitalised on Paul Warhurst's attempted back header to smash the ball home.
Bolton came back wonderfully and within minutes of the second half starting had levelled matters when Jamaican Ricardo Gardner fired home a fantastic shot from 30 yards.
However, Derby were not to be denied and they were back in the lead just seven minutes later when Fabrizio Ravanelli looped home a header after a great cross from Paul Boertien.
The Rams sealed the win with a penalty four minutes from time. Lee Morris had broken clear of Bolton's defence, only to be blatantly brought down by Jussi Jaaskalainen - who was immediately dismissed.
Danny Higginbotham was handed the task of sealing the win and he duly obliged to give John Gregory's men the much needed win.
Bottom-of-the table Leicester City threw away a two-goal lead at St Mary's as Southampton came back to claim a 2-2 draw.
Leicester took the lead after 21 minutes when Paul Dickov produced a great cross, which Brian Deane flicked on and over the stranded Paul Jones.
Deane then grabbed his and Leicester's second just two minutes when he turned home the ball after Muzzy Izzet's effort cannoned of bar and post.
Marian Pahars, playing in an unusual midfield role, then gave The Saints hope when he broke into the area and got on the end of Anders Svensson's cross to head past Ian Walker.
But just when Leicester looked to be hanging on for only their fourth win of the season, Southampton were awarded a penalty after Matt Elliott brought down substitute James Beattie.
Pahars was given the task and he made no mistake to give Saints a share of the spoils.
Click on fixture for full match summary
Bolton 1-3 Derby
Chelsea 4-0 Sunderland
Everton 2-1 Fulham
Newcastle 2-2 Ipswich
Southampton 2-2 Leicester
West Ham 3-5 Manchester United
Click here for updated league table
