Foster will start his first derby on Sunday when United face their loval rivals at Old Trafford.
“City will be up there but this season will be too soon for them,” he told the News of the World.
“The ‘big four’ will probably be there come the end of the season. Hopefully United will be at the top.
“We are genuinely not thinking about City. It will take time for them to gel. When you get a lot of players come in it’s hard to know what other players are doing.”