Manchester United are now top of the Barclays Premier League after they beat West Brom 2-0 and Manchester City lost 1-0 at Swansea on Sunday afternoon.
City dropped off the summit for the first time since October after Luke Moore's late header saw Swansea once again upset one of the top-flight big guns at the Liberty Stadium.
Substitute Moore had only been on the field a matter of minutes when he rose at the far post to head Wayne Routledge's cross beyond Joe Hart.
It could have been worse for City had Scott Sinclair converted an early penalty, although Mario Balotelli and Sergio Aguero spurned good chances for the visitors and Micah Richards had a header ruled out for offside in the final moments.
Wayne Rooney was the hero for United as he struck either side of the interval to help his side maintain their title charge with victory over the Baggies at Old Trafford.
The striker touched home Javier Hernandez's right-wing cross to settle a few nerves before belting home from the spot after Ashley Young had been fouled by Keith Andrews.
It took Rooney on to 26 goals for the season, although Ashley Young and Javier Hernandez wasted late chances to increase the lead still further.
The Red Devils now hold a one-point advantage at the top of the standings.
Sir Alex Ferguson: "It's a surprising day for us I suppose.
"I'm happy to be there because only a few weeks ago we were five points, and at one time seven points, behind and now we're a point ahead.
"So we've turned around eight points and it's a credit to the players and also to the resilience of our squad because, as everyone knows, we've had a lot of injuries.
"I don't care about being top of the league just now. More important was our own performance.
"We needed that performance after the disappointment of Thursday. But the players played fantastic football today and I was really, really pleased with that part."
Roberto Mancini remains confident Manchester City can win the Premier League after Swansea dealt a severe blow to their title hopes with a 1-0 victory at the Liberty Stadium.
Roberto Mancini: "It's been difficult the last four days for me, but football is this - sometimes you can lose.
"I don't think that we deserved to lose this game. I should say that Swansea played very well in the first 30 minutes. They played very good football.
"But in the second half we had control of the game. We missed three or four chances on the counter-attack and we conceded a stupid goal.
"Now it's important that we are very confident together because it changes nothing. It is better to stay on the top and now we are behind, but this doesn't change our targets.
"I think that this championship maybe will be decided three games from the end."
Wigan battled to a 1-1 draw at Norwich in the day's other game, but it was not enough to lift them off the bottom of the table.
Wes Hoolahan clipped in Simeon Jackson's cross to put the Canaries in front after 10 minutes.
However, Wigan grew into the match and eventually netted a deserved equaliser through a well-taken finish by Victor Moses on 68 minutes.
Source: FOOTYMAD
