Yesterday’s Manchester derby between Manchester United and Manchester City saw the world’s tiniest pitch invader: a little mouse.

The little guy saw a big patch of green grass at Old Trafford and figured it would be a great place for some scampering.

Now you know why cats are needed to run around Citi Field & Wrigley Field: To keep the mice from thinking they can just run around wherever they damn well please.

Video: A mouse joins in the Manchester derby [Off The Post] & [101 Great Goals]

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