Often derided for a lack of atmosphere, the stadium tend to be at its noisiest for the biggest of matches.
For all kinds of reasons, this fixture is among the most important. Rooney just hopes the Red Devils supporters recognise it.
"The atmosphere at Old Trafford for big games is great," he said. "I am sure the fans realise this is a really important match for us and will be at their best.
"When they are like that it brings energy into our play. We will need them this weekend."
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