The Football Association will speak to both Manchester clubs to try to avoid any flashpoints during next week's Carling Cup semi-final decider at Old Trafford.
It is expected the FA will officially confirm Gary Neville will face no sanction over his one-fingered gesture to Carlos Tevez during Tuesday's first-leg, when City won 2-1.
Although there are photographs showing Neville's reaction, as Tevez is not in the frame and the incident was not captured on TV, it is virtually impossible for the FA to prove what happened and the incident itself was regarded as minor.
Nevertheless, the FA acknowledge the simmering tension between the two sides could lead to an escalation of the problem next week, when the red and blue halves of Manchester face each other once more to decide who will face Aston Villa at Wembley on February 28.
Although the desire for cool heads will be kept informal, the FA hope the two clubs heed their message given the huge number of people who will be watching a match which has captured attention far beyond the city itself.
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