Manchester City boss Roberto Mancini thinks his team are in a strong position to win the Premier League title - because they have already played their close rivals away.
City have won all eight of their matches at Etihad Stadium.
"At home it won't be easy but it will be better for us."
Mancini's team have scored 25 goals in eight Premier League matches at Etihad.
And he added: "In the next two months United have to play Tottenham, Chelsea and Arsenal away - and City. This is important.
"But we know United are a really strong team. We can't think we can win the title without fighting against United. This is impossible."
Mancini was pleased to see his team bounce back from their first defeat of the season to beat Arsenal 1-0.
City lost to Chelsea on Monday, and slipped to second in the Premier League table after Manchester United beat QPR.
But, thanks to David Silva's second-half goal, Mancini's side restored their two-point cushion at the top.
Mancini added: "It was important [to hit back], because United are having a good season like Manchester City.
"We are strong, they are strong, but we know that the season is long.
"It could be in the season that we could go into second position but we know that it's important to stay on top in the end."
In an entertaining game, City could have made it easier for themselves if Sergio Aguero had taken an early chance. They also hit the post through Pablo Zabaleta.
But the hosts were thankful for a fine performance by keeper Joe Hart, who made saves from Robin van Persie, Thomas Vermaelen and Theo Walcott.
Van Persie also had a goal disallowed for offside.
Arsenal's loss was their first in nine games and leaves them 12 points off Manchester City at the top of the table.
Gunners boss Arsene Wenger said it would now be very difficult to win the title, but said they "will try".
"This was a game we couldn't afford to lose," Wenger said. "It's difficult to take but we will continue to fight."
Wenger said they were caught out in defence once temporary right-back Johan Djourou was taken off prior to the goal.
His injury adds to the problems in defence which led to them starting the game with four centre-backs and, when he went off just after half-time, Laurent Koscielny was forced to fill in at full-back, with City subsequently exploiting a clear gap down Arsenal's right.
"We suffered from the fact that we had to completely reshuffle our defence. We are too short on full-back positions at the moment and we cannot bring another one [onto the field]," Wenger said.
"Overall we had a good performance, we gave absolutely everything and we were unlucky as well because we had the chances. The offside decisions [for our goal and David Silva's goal] are not completely convincing.
"The game could have finished 1-1, 2-0 for them or 1-0 for us. We know we are close to [City] and you have seen that today."