Van Persie's goal was all the more extraordinary as, prior to Wednesday's match, United had conceded the first goal 13 times already this season. "We've got the three points and are still ahead in the league," United manager Alex Ferguson said.
"We played a lot of good football but we never quite finished them off. West Ham made it difficult for us."
Ahead of cityUnited remained just a point in front after reigning champions and local rivals Manchester City, who won 2-0 away to Wigan. City, the only unbeaten side in the top flight, looked like they might be held to a frustrating draw before striker Mario Balotelli scored his first league goal of the season in the 69th minute. And three minutes later England midfielder James Milner made it 2-0 with a powerful shot. "It was important because it's always a difficult game because they play very well," City manager Roberto Mancini told Sky Sports.
European champions Chelsea suffered their second straight home goalless draw, under interim manager Rafael Benitez, a derby stalemate with Fulham doing little for his approval rating with the sceptical Stamford Bridge faithful.
Chelsea moved up one place to third but, more significantly, they are now seven points behind United.