Police chiefs have vowed they will "clamp down" on anyone intent on causing trouble around Monday's crucial Manchester derby.
Although Greater Manchester Police praised the respective supporters for their good behaviour at the FA Cup third-round tie at the Etihad Stadium in January, which United won 3-2, there have been problems in the past.
Twenty-nine people were arrested after the Carling Cup semi-final first-leg tie between the two sides two years ago, and with the latest meeting almost certainly going to decide the destination of this season's Premier League title, tensions are bound to be heightened.
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