City may yet still lose Carlos Tevez, but they have strengthened the side already and more new faces are expected soon.
Vidic is not trying to give the impression that he spends time worrying about what the Berties are doing this week, but he does accept that City will be their main challengers to the title this season.
Vidic is anxious not to be seen spending time worrying about United's rivals as the countdown to a new campaign begins, but is certain City will pose their biggest challenge yet for major honours.
"It is clear Manchester City have the money and they will sign new players," said the Serbian defender.
"They will definitely be in position to fight for the league.
"But we have to focus on ourselves. We have to think about what happens at our door, not our neighbours', and I believe we have enough good players and a good team to challenge for the trophy."