Ricardo Vaz Te’s first half opener had given the home side the lead but United levelled the score after 31 minutes through Antonio Valencia, following good work from Shinji Kagawa.
West Ham emerged for the second half the brighter side, and they seemed to be on course for a shock win when Mohamed Diame angled a wonderful left-footed strike into the bottom corner of the United net.
The Premier League table-toppers refused to accept defeat, however, and once again restored parity when Robin Van Persie slotted into an empty net after Kagawa's stunning long-range effort ricocheted back off both posts to the Dutchman's feet.
Sir Alex Ferguson named a strong, attacking side, with Wayne Rooney restored to a more familiar attacking role after playing in midfield in Saturday’s 2-0 win over Stoke City.
Hammers boss Sam Allardyce made just one change to the side that had drawn 1-1 with Southampton, replacing James Tomkins with Winston Reid.
The home side started the game the brighter of the two, pressing United in possession and forcing mistakes from Ferguson’s seemingly nervy side. Andy Carroll came close to giving his side the lead within the opening five minutes, clipping the United upright after a low strike from 18 yards.
West Ham continued to pile on pressure and deservedly took the lead after 17 minutes. Matt Jarvis got beyond Rio Ferdinand to stage a cross into Carroll, who had the beating of Patrice Evra in the air.
Carroll then knocked the ball down to Vaz Te, who turned home from close range to give the Hammers the lead.
United fought back, however, and equalised just after the half hour mark through Valencia. Good work from Van Persie on the left released Kagawa to the byline, and the Japanese star squared for the Ecuadorian winger to tap into an empty net.
West Ham remained on top, however, and started the second half just as they had begun the first - and it was no surprise when they regained the lead as Diame angled a left-footed shot past David De Gea in the United goal.
Carroll, who was causing problems for the United defence with his physical presence, almost caught out De Gea from 35 yards, but the striker’s effort drifted wide with the Spanish keeper backtracking frantically.
But United kept scrapping and slowly came into the ascendancy. First Jussi Jaaskelainen pulled off a magnificent close range stop from Van Persie, then Rooney saw an effort cleared off the line by Gary O’Neil after an unconvincing save by the West Ham goalkeeper.
Alex Ferguson's men finally restored parity with 13 minutes remaining when Van Persie slotted home. Kagawa’s superb turn-and-shoot effort from the edge of the box struck both posts and fell straight to the Dutchman who thundered the ball into the roof of the net. West Ham were hard-done-by with the equaliser, however: replays showed that Van Persie was a clear yard offside at the time of Kagawa's effort.
United were presented with one final chance to take all three points, but substitute Javier Hernandez couldn’t turn home Ryan Giggs’s cross, with Carroll putting in a last ditch tackle to preserve a point for the Hammers.
West Ham - Jaaskelainen 7, Demel 6, Reid 5, Collins 5, O’Brien 5, Nolan 6, Diame 7, Jarvis 7, O’Neill 6, Vaz Te 6, Carroll 8. Subs: Noble 5, Collison N/A, Taylor N/A.
Manchester United – De Gea 7, Rafael 5, Vidic 6, Ferdinand 4, Evra 5, Valencia 6, Carrick 5, Jones 5, Kagawa 7, Rooney 5, Van Persie 7. Subs: Giggs 5, Hernandez N/A.
MAN OF THE MATCH
Andy Carroll (West Ham): The West Ham frontman was the physical presence his side needed him to be. Not many go head to head with Nemanja Vidic and come out on top but Carroll had the beating of the United captain tonight.