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Scott Heppell, Associated Press
Manchester United's Wayne Rooney, left, is seen with manager Alex Ferguson, right, after being took off during their English Premier League soccer match against Newcastle United at the Sports Direct Arena, Newcastle, England, Wednesday, Jan. 4, 2012.

LONDON — Although Arsenal and Chelsea have been his team's biggest rivals in recent years, manager Alex Ferguson says a club much closer to home will be Manchester United's chief adversary for years to come.

Propelled by the cash of its billionaire owners, Manchester City has become a regular contender for trophies for the first time in a generation.

The two Manchester clubs meet for the third time this season on Sunday in the third round of the FA Cup in what is rapidly emerging as the country's most high-profile matchup.

Ferguson says "the way we and our supporters should look at it is that we may as well get used to it because they are not going to go away."