The title race swung dramatically back towards the red half of Manchester yesterday after Wayne Rooney fired United top of the Premier League, as cross-town rivals City slipped up.

While Rooney claimed his side "deserve" to be top by a point following their 2-0 win over West Bromwich Albion, Roberto Mancini stated that City's 1-0 defeat to Swansea City "was not critical". Luke Moore's winner ensured Sir Alex Ferguson's side head the division for the first time since 15 October — apart from 24 hours in mid-February.

Rooney, who now has 26 goals for United, said: "This is where we want to be at the finish, I don't think we've had the credit we deserve these last few months. Europe has been disappointing," he said of United losing their last two Europa League games. "But we have played well against the big teams recently, we haven't always been at our best but we have got the wins and we fully deserve to be at the top."

United have beaten Tottenham Hotspur and Liverpool and drawn at Chelsea in recent weeks in a run of 22 points from a possible 24 in their last eight outings. City, meanwhile, have lost three times since New Year's Day and Sir Alex Ferguson said of this turnaround: "It's an extra bonus, we didn't expect that. I think at this time of the season I always say points will be dropped. We've got to the stage now where if we can keep winning – that's the name of the game anyway for both of us – then the games whittle away and you run out of games.

"I don't care about being top of the league just now, [I'm] just happy to be there because only a few weeks ago we were seven points behind at one time and now we're one point ahead. So we've turned round eight points and it's credit to the players and also the resilience of our squad because as everyone knows we've had a lot of injuries."

Mancini admitted this is a testing moment for him after the defeat at the Liberty Stadium followed the 1-0 reverse at Sporting Lisbon in the Europa League on Thursday.

"The last four days have been difficult for me but this is football," he said. "Sometimes you can lose. I don't think we deserved to lose this game.

"Swansea played very well for 30 minutes but in the second half we controlled the game. We missed three or four chances on the counterattack to score. That is the problem at the moment, and then we conceded a stupid goal. A team like us cannot concede a goal like this. Maybe we were tired at the start. That's normal after seven months because we're playing three games in a week."

Mancini urged his players to focus only what they can do, with the meeting with United on 30 April at the Etihad shaping up to be the title decider. "It's not important what United did. We will fight against them until the end. We have 10 games to finish the championship and every week it can change. It's important that we remain very compact together. It's better to be at the top but it doesn't change anything. This championship is very long and there is time to go. We won't change our target. This was not a critical game. The championship will be decided three games from the end of the season.

"I'm confident this changes [nothing]. We've been at the top for six months. We might not be at the top now but United had an easy game. We are just one point behind. We know this can happen that United can go top. We've been there always but it won't change anything."

"We lost two games in four days, which is a bad moment. We've lost a few players through injury which may be a problem [including Vincent Kompany, the captain]. That's a bigger problem than losing the games but we have time to recover. The season is long but it doesn't change anything. The same thing can happen to United in their next game and we could be top again."

Yet with United playing Woverhampton Wanderers on Sunday before City play Chelsea at home on the following Wednesday Mancini's team could be facing a four-point gap going into that encounter that could prove a psychological disadvantage.