Professor Neil Fowler
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Farah v Bolt - who would win?

29 July 2013 Last updated at 16:23 BST

Mo Farah has challenged Usain Bolt to a race - but who would win?

Farah usually runs long distances over 5,000m while Bolt competes in the 100m and 200m sprints.

Bolt has already said that 1,500m would be too far.

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