Robin van Persie's first minute strike proved enough for Manchester United to maintain its one-point lead at the top of the Barclays Premier League with a hard-fought 1-0 win over West Ham.
Van Persie saw his strike deflect into the net off Hammers defender James Collins but United struggled to build on its dream start and was fortunate when goalkeeper Anders Lindegaard made a fine save to deny Carlton Cole late on.
United's fourth straight home win kept City at arm's length after the champions' 2-0 victory at Wigan on Wednesday.
"We got a great start," United manager Alex Ferguson said. "You hope to go on from a start like that and some of our football was very good, but we never quite finished them off."
On his return to Old Trafford last Friday for the first time since he was sent packing by Ferguson six years ago, Ruud van Nistelrooy declared his hope that van Persie would eventually eclipse his United career.
As Van Nistelrooy scored 150 times in five seasons with the Red Devils, van Persie evidently has some way to go.
The 29-year-old's 12th goal came in his 18th game, one fewer than Van Nistelrooy managed it in following his arrival from PSV Eindhoven. And any latecomers missed it.
With a side lacking any orthodox wingers, van Persie checked inside from the left flank, then made his way to the edge of the area as Michael Carrick exchanged passes with Anderson.
Van Persie swiveled past Winston Reid as he collected Carrick's forward pass, then profited from James Collins' desperate attempt to block, which only sent the ball looping over Jussi Jaaskelainen and into the net, making it the quickest goal in the league this campaign.
Van Persie now has 12 goals in 18 matches in all competitions this season after his move from Arsenal in August.
"Robin van Persie is a quality player and we have largely kept him quiet," West Ham manager Sam Allardyce said. "But he will score 20 goals for Manchester United, maybe 30, (this campaign)."
His effort had more than a hint of good fortune in it, flicking a pass from Michael Carrick over marker Winston Reid before seeing his attempted lob loop off Collins into the net.
United failed to kick on, though, and was kept largely quiet by a compact West Ham side.
With Wayne Rooney struggling to make an impact as an attacking midfielder, West Ham tried to respond through shots by Kevin Nolan and Andy Carroll that both flew off target.
United ended up hanging on for a scrappy victory, with the team yet to click this season.
"Of course, City are on our tails so it is going to be a long season," Ferguson said.
The first Manchester derby takes place at City's Etihad Stadium on Dec. 9.
Information from Press Association and The Associated Press was used in this report.